Pick which word below is the subject of the sentence:

The quarterback threw the ball down the field.
A) the quarterback
B) The field
C) the ball
D) down

A) the quarterback

The subject of the sentence is "the quarterback." So, the answer is A) the quarterback.

The subject of a sentence is the noun or pronoun that performs the action of the verb. To determine the subject, we need to ask ourselves "Who or what is doing the action?" In this sentence, the action is "threw," and the question we should ask is "Who threw the ball?" The answer is "the quarterback." Therefore, the subject of the sentence is "the quarterback."

So, the correct answer is A) the quarterback.