In the following question, choose the pair of words that best fits the blanks to complete the sentence meaningfully.

Although he ________________________ that the ancient manuscript was a forgery, the curators discovered no evidence to substantiate the historian's ______________________ assertion.

Correct Answer: alleged, purported

To choose the correct pair of words to fill in the blanks, let us analyze the context and structure of the sentence step-by-step.

Sentence Structure and Clues:

1. The sentence begins with the word "Although", which indicates a contrast between what the historian claimed/stated and what evidence was actually found.

2. First Blank: "Although he ________________________ that the ancient manuscript was a forgery..."
Here, we need a verb in the past tense that means to claim or state something without proof. The word "alleged" fits appropriately because it means to claim or assert that someone has done something or something is the case, typically without providing proof.

3. Second Blank: "...the curators discovered no evidence to substantiate the historian's ______________________ assertion."
Here, we need an adjective describing the historian's claim/assertion, given that no evidence was found to back it up. The word "purported" means appearing or stated to be true, though not proven, which matches the idea of an unsubstantiated assertion.

Evaluating the Options:

• angst, hysterical: "angst" is a noun (meaning anxiety) and does not fit grammatically into the first blank.
• alleged, purported: Fits both grammatically and contextually. "Alleged" functions as the verb for making an unproven claim, and "purported" functions as an adjective describing a claimed but unverified assertion.
• frightened, grumpy: Neither word makes sense in the context of analyzing an ancient manuscript.
• level, believed: Does not create a meaningful sentence in this context.
• referred, fueled: Does not logically fit the structure or meaning of the sentence.

Thus, the pair of words that best completes the sentence meaningfully is "alleged, purported".