Let's break down the sentence to understand the context and required meaning for the blank:
- "Because she was famed for her objectivity and temperate attitude...": This part establishes the news anchor's usual reputation. "Objectivity" means impartiality, and "temperate attitude" means calm, moderate, or restrained behavior.
- "...the $\qquad$ offered by the news anchor at the protest rally seemed especially uncharacteristic.": This part tells us that whatever was "offered" was not objective or temperate; it was highly unusual for her. Therefore, the blank needs a word that describes strong, biased, or emotionally charged language, an angry speech, or harsh criticism.

Let's evaluate the given options:
- A. account: A report or description of an event. This is a neutral term and is characteristic of a news anchor, so it does not fit "uncharacteristic."
- B. accolades: Praise or approval. This is positive and doesn't fit the context of something uncharacteristic for a neutral observer at a potentially contentious event like a protest rally.
- C. invective: Insulting, abusive, or highly critical language. This perfectly describes something that would be uncharacteristic for someone known for objectivity and a temperate attitude.
- D. diatribe: A forceful and bitter verbal attack against someone or something. This also perfectly fits the meaning of strong, aggressive, and highly critical language, making it a strong synonym for "invective" in this context.
- E. perspective: A particular attitude toward or way of regarding something; a point of view. While a news anchor might offer a perspective, doing so is not inherently "uncharacteristic" for someone famed for objectivity unless that perspective is extremely biased. It lacks the strong negative connotation implied by the context.
- F. insinuations: An unpleasant hint or suggestion of something bad. This implies subtle or indirect negative implications, not the strong, overt, and uncharacteristic verbal attack implied.

Both invective and diatribe fit the context, describing a strong, critical, and uncharacteristic verbal outburst from someone usually known for their calm objectivity.