Text completion: restate the evidence in one word

Correct answer: C

Everything after the comma is the evidence the blank must summarize: primary sources (letters, diaries, court records), explicitly contrasted with rumor and speculation.

• (C) documented means supported by documentary evidence. Letters, diaries, and court records are documents, and “rather than rumor or speculation” seals it. Correct.
• (A) conjectural means based on conjecture, which is what the sentence says the account avoids. It is the antonym of the evidence.
• (B) partisan means biased toward one side. Sources can be thorough and biased at once, but nothing in the sentence addresses bias; the contrast is evidence versus rumor.
• (D) cursory means hasty and superficial, which collides with “thoroughly” and with the weight of the source list.
• (E) lyrical describes style, not evidentiary basis; the sentence never mentions prose quality.

This is the most common hard-level pattern: no pivot word at all, just an appositive that defines the blank. Compress the evidence into a single adjective before you look at the choices. “Well-sourced” is the natural compression, and documented is its exact match.