Deep-sea ecosystems contain some of the most extreme environments on Earth, where creatures survive without sunlight and under crushing pressure....

Sentence Structure

• Deep-sea ecosystems contain some of the most extreme environments on Earth, where creatures survive without sunlight and under crushing pressure.
• These species are not the only marine organisms adapted to hostile conditions (?) populations living near hydrothermal vents endure water temperatures that exceed 400 degrees Celsius.
• Where (?):
  • Common across all choices: conditions + however
  • What varies: punctuation before and after 'however'
    • A. conditions, however,
    • B. conditions; however,
    • C. conditions, however;
    • D. conditions however,

Understanding the Meaning

The first sentence sets the scene:

• Deep-sea ecosystems have extreme environments
  • creatures there survive without sunlight and under crushing pressure

The second sentence starts:

• 'These species' (referring back to those creatures)
  • are not the only marine organisms adapted to hostile conditions

This is where we have the blank. Let's look at the choices:

• They all include 'however'
• The question is what punctuation goes before and after it

To see what works here, let's read the rest of the sentence and understand what it's saying!

The sentence continues:

• 'populations living near hydrothermal vents endure water temperatures that exceed 400 degrees Celsius'

Now let's understand what this complete sentence is telling us:

• First part: 'These species are not the only marine organisms adapted to hostile conditions'
  • This is making a statement about the deep-sea creatures
  • It's saying they're not alone in being adapted
• 'however' signals a contrast or addition
• Second part: 'populations living near hydrothermal vents endure water temperatures that exceed 400 degrees Celsius'
  • This is giving another example of organisms in hostile conditions
  • It's a complete statement on its own - populations endure extreme temperatures

What do we notice about the structure here?

• Both parts are complete thoughts that could stand alone as sentences:
  • 'These species are not the only marine organisms adapted to hostile conditions' - complete thought with subject (these species) and verb (are)
  • 'Populations living near hydrothermal vents endure water temperatures that exceed 400 degrees Celsius' - complete thought with subject (populations) and verb (endure)
• We're connecting these two complete thoughts with the word 'however'
• When 'however' connects two complete thoughts, we need:
  • A semicolon before 'however' (to separate the two complete thoughts)
  • A comma after 'however' (this is the standard punctuation after this transitional word)

So we need: conditions; however, - The correct answer is Choice B.

Grammar Concept Applied

Connecting Two Complete Thoughts with 'However'

When you want to connect two complete thoughts (called independent clauses in grammar terms) using a transitional word like 'however,' you need specific punctuation:

The Pattern:

• Complete thought #1 + semicolon + however + comma + complete thought #2

Example 1:

• Complete thought: 'The experiment was carefully designed'
• Complete thought: 'the results were inconclusive'
• Connected properly: 'The experiment was carefully designed; however, the results were inconclusive.'

Example 2:

• Complete thought: 'Many students prefer studying in groups'
• Complete thought: 'some work better alone'
• Connected properly: 'Many students prefer studying in groups; however, some work better alone.'

In our question:

• Complete thought #1: 'These species are not the only marine organisms adapted to hostile conditions'
• Complete thought #2: 'populations living near hydrothermal vents endure water temperatures that exceed 400 degrees Celsius'
• Correctly connected: 'These species are not the only marine organisms adapted to hostile conditions; however, populations living near hydrothermal vents endure water temperatures that exceed 400 degrees Celsius.'

Why this punctuation?

• The semicolon acts as a strong separator between the two complete thoughts (stronger than a comma)
• The comma after 'however' follows the standard convention for transitional words at the beginning of a clause
• Together, they create a grammatically correct connection that shows the relationship between the two ideas