Archaeologists continue to investigate when ______ though recent excavations have provided compelling new evidence about the site's origins.

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

• Archaeologists continue to investigate
• when [?]
• though recent excavations have provided compelling new evidence
• about the site's origins.

Understanding the Meaning

The sentence starts by telling us what archaeologists are doing:

• 'Archaeologists continue to investigate when ______'

This is where we have the blank.

Let's look at the choices - they're asking us to decide between:

• Question form: "did the ancient city collapse?" or "the ancient city did collapse?"
• Statement form: "the ancient city collapsed."
• Question mark vs. period

To see what works here, let's think about what "investigate when" means!

When archaeologists "investigate when" something happened, they're exploring the question of "when did this happen?" But here's the key - this question is embedded inside a larger statement about what the archaeologists do.

Let's compare:

• If you're ASKING a question directly: "When did the ancient city collapse?"
  • This uses question word order: "did...collapse"
  • This uses a question mark

• But if you're making a STATEMENT about investigating a question: "Archaeologists investigate when the ancient city collapsed"
  • This uses statement word order: "...collapsed"
  • This uses a period (because the whole sentence is a statement, not a question)

What do we notice about the structure here?

• This is what's called an embedded or indirect question
  • The question ("when did it happen?") is tucked inside a statement about what archaeologists do
  • When a question is embedded this way, it changes form - it uses statement word order and follows the punctuation of the main sentence

• The overall sentence is telling us something (not asking us something)
  • So we need a period, not a question mark

So we need: "the ancient city collapsed." - statement word order with a period.

The sentence continues: "though recent excavations have provided compelling new evidence about the site's origins."

This confirms our answer - the entire sentence is a statement about archaeological work, with a contrast introduced by "though."

The correct answer is D.

GRAMMAR CONCEPT APPLIED

Embedded Questions (Questions Within Statements)

When a question is embedded within a larger statement (these are called indirect questions in grammar terms), the structure changes from a direct question:

Direct Question (standing alone):

• "When did the ancient city collapse?"
• Question word order: "did...collapse"
• Question mark

Indirect Question (embedded in statement):

• "Archaeologists investigate when the ancient city collapsed."
• Statement word order: "the ancient city collapsed"
• Period (because the overall sentence is a statement)

Common embedding phrases that create indirect questions:

• "investigate when..." → "investigate when it collapsed"
• "wonder whether..." → "wonder whether it's true"
• "asked why..." → "asked why she left"
• "know how..." → "know how it works"

In this question:

• The phrase "investigate when" signals an embedded question
• So we need statement word order ("the ancient city collapsed") not question word order ("did the ancient city collapse")
• We need a period because the whole sentence is making a statement about what archaeologists do, not asking us a question