Before examining the magnified images, Banerjee had hypothesized that because the layered fibers retained ______ would not reach the tissue. The images later disproved this prediction.
Which choice completes the text so that it conforms to the conventions of Standard English?
For a challenging boundaries question, trace the full hierarchy of clauses rather than judging only the words nearest the blank. In particular, identify complementizers such as “that” and subordinators such as “because”; then determine whether the material on each side of a proposed mark is independent or dependent before choosing among a comma, semicolon, period, and colon.
Hints
Find the hypothesis
Identify all the words that belong to the prediction introduced by “had hypothesized that.”
Examine the opening word
Determine whether the clause beginning with “because” can stand alone or must connect to another clause.
Test each boundary
For each stronger punctuation mark, check whether all the material before it forms a complete sentence in the surrounding syntax.
Step-by-step Explanation
Map the sentence structure
The verb “had hypothesized” introduces a that-clause: “that because the layered fibers retained moisture, oxygen from the surrounding air would not reach the tissue.” The entire prediction is contained within this embedded clause.
Identify the dependent clause
“Because the layered fibers retained moisture” is a dependent clause. Within the that-clause, it comes before the main clause “oxygen from the surrounding air would not reach the tissue.”
Place the boundary
A comma separates the introductory dependent clause from the main clause that follows. Therefore, “moisture, oxygen from the surrounding air” correctly completes the sentence.