The hieroglyphics are ancient symbols ______ based on current research, represent one of humanity's earliest systems of written communication.

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

• The hieroglyphics
  • are ancient symbols
    • that (?) based on current research, represent one of humanity's
      • earliest systems of written communication.

Understanding the Meaning

Let's start reading from the beginning:

The sentence tells us:

• "The hieroglyphics are ancient symbols"
  • Pretty straightforward - we're talking about hieroglyphics and identifying what they are.

Now we get more specific information:

• "that... represent one of humanity's earliest systems of written communication"
  • This is describing WHICH symbols they are - they're symbols that represent one of the earliest writing systems.

This is where we have the blank - right after "that."

Let's look at the choices:

• We need to decide what punctuation (if any) comes after "that"
• The options are: a colon, a comma, a semicolon, or a dash

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

The sentence continues:

• "based on current research, represent one of humanity's earliest systems of written communication"

Now let's understand what this structure is telling us:

• The main idea being communicated is:
  • "that represent one of humanity's earliest systems of written communication"

• But there's a phrase in the middle:
  • "based on current research"
  • This is telling us HOW we know this information - it's based on current research
  • Notice there's already a comma AFTER "research"

What do we notice about the structure here?

• "Based on current research" is an interrupting phrase
  • It's adding extra context in the middle of the thought
  • The main flow is: "that represent one of humanity's earliest systems..."
  • The "based on current research" part is inserted to give us context

• When you have an interrupting phrase like this, you need to set it off with commas on BOTH sides
  • One comma to open the interruption
  • One comma to close it

• Since there's already a comma after "research," we need a comma after "that" to open the interruption

So we need: that, based on current research, represent...

The correct answer is Choice B: that,

GRAMMAR CONCEPT APPLIED

Setting Off Interrupting Phrases with Commas

When you insert a phrase that interrupts the main flow of a sentence to add extra information or context, you need to set it off with commas on both sides (called parenthetical elements in grammar terms):

Pattern:

• [Beginning of main thought], [interrupting phrase], [continuation of main thought]

Example 1:

• Without interruption: "The results show a significant improvement"
• With interruption: "The results, according to the study, show a significant improvement"
• Comma before "according to the study" opens the interruption
• Comma after "study" closes the interruption

Example 2:

• Without interruption: "The team completed the project ahead of schedule"
• With interruption: "The team, despite numerous setbacks, completed the project ahead of schedule"
• Comma after "team" opens the interruption
• Comma after "setbacks" closes the interruption

How this applies to our question:

• The main thought: "that represent one of humanity's earliest systems..."
• The interruption: "based on current research"
• Needs commas on both sides: "that, based on current research, represent..."

The key is recognizing when a phrase is interrupting the main flow versus being part of it. If you can remove the phrase and the sentence still flows naturally, it's an interrupting element that needs comma pairs.