Jetties—long, narrow structures that extend from a landmass into the water—are often constructed to protect coastlines from erosion. Jetties can...

Let's begin by understanding the meaning of this sentence. We'll use our understanding of pause points and segment the sentence as shown - understanding and assimilating the meaning of each segment bit by bit!

Sentence Structure

• Jetties
  • —long, narrow structures
    • that extend from a landmass into the water—

• are often constructed
  • to protect coastlines from erosion.

• Jetties can sometimes have the opposite effect (?)
• obstructing the natural flow of sand along the shore
  • can lead to increased erosion in some areas.

• Where (?): [, though + punctuation that varies]

Understanding the Meaning

The first sentence tells us what jetties are and why they're built:

• Jetties are long, narrow structures that extend into water
• They're constructed to protect coastlines from erosion

The second sentence presents a contrast:

• "Jetties can sometimes have the opposite effect"
  • Instead of preventing erosion, they can actually cause it

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

• All of them have "though" but with different punctuation around it
• A has: effect, though;
• B has: effect, though
• C has: effect; though
• D has: effect, though,

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

• "obstructing the natural flow of sand along the shore can lead to increased erosion in some areas"
  • This explains HOW jetties cause the opposite effect
  • By blocking the natural movement of sand, they increase erosion rather than prevent it

So the complete picture is:

• The sentence is making a point (jetties can backfire) and then explaining the mechanism (by obstructing sand flow)

What do we notice about the structure here?

• "Jetties can sometimes have the opposite effect, though"
  • This is a complete thought - it has a subject (Jetties) and a verb (can have)
  • It could stand alone as a sentence
  • "Though" here is acting as a transitional word at the end

• "obstructing the natural flow of sand along the shore can lead to increased erosion in some areas"
  • This is ALSO a complete thought
  • Subject: "obstructing the natural flow..." (the whole phrase)
  • Verb: "can lead"
  • It could also stand alone

So we have two complete thoughts that need to be properly connected.

When you have a transitional word like "though" at the end of the first complete thought, you need:

• A comma before "though" to set it off
• A semicolon after "though" to properly separate the two complete thoughts

The correct answer is A: effect, though;

GRAMMAR CONCEPT APPLIED

Connecting Independent Clauses with Transitional Words and Semicolons

When you have two independent clauses (complete thoughts that could stand alone as sentences) and you use a transitional word at the end of the first clause, you need specific punctuation:

Pattern: Independent clause, transitional word; Independent clause.

Example 1:

• Without transition: "The experiment failed. The results were inconclusive."
• With transition: "The experiment failed, though; the results were inconclusive."
  • First independent clause: "The experiment failed, though"
  • Second independent clause: "the results were inconclusive"
  • The comma sets off "though," and the semicolon separates the two complete thoughts

Example 2:

• "The team won the championship, however; they faced many challenges along the way."
  • Comma before the transitional word
  • Semicolon after it to separate the independent clauses

In our question:

• First independent clause: "Jetties can sometimes have the opposite effect, though"
• Second independent clause: "obstructing the natural flow of sand along the shore can lead to increased erosion in some areas"
• The comma before "though" sets it off as a transitional element
• The semicolon after "though" properly separates the two complete thoughts

This is different from using a semicolon with transitions at the BEGINNING of the second clause (like "however," "therefore"), where the pattern is: Independent clause; transitional word, independent clause. Here, "though" ends the first clause, so it gets: comma before it, semicolon after it.