Question

complete the sentence. in the early 1900s, most deaths in the united states were caused either by pneumonia or _______, which spread quickly in overcrowded cities. by influenza influenza

Explanation:

The sentence uses the structure "either by X or Y" for parallelism. Since "by" is already included before the first item ("pneumonia"), we only need the noun for the second item to maintain grammatical consistency.

Answer:

influenza