Answer:
D. therefore
Step-by-step explanation:
The correct transition word that fits the passage is therefore. So, the sentence will read thus:
General Washington could not rely on Henry Knox to supply regular reports about the yellow fever epidemic. He therefore wrote to the comptroller of the treasury, Oliver Wolcott, in an attempt to get an update on the situation in Philadelphia.
"Therefore" is the transition word that links the first information the passage gave in the first sentence to the second information in the passage. So, it means that since General Washington could not rely on Knox, that led him to write to Wolcott.
Transition words which are also known as linking words refers to words or phrases that actually show the connection that exists between sentences, paragraphs or sections of a passage or speech. These words tend to signal how ideas relate to each other in a passage.