Answer:
A. Attentive.
Explanation:
The baseball whizzed by my bat and the umpire called "Strike!" The crowd was silent but attentive as the pitcher prepared to throw what could be the final pitch of the championships.
In order to qualify the noun "crowd" and complement the action they were engaged in; an adjective such as "attentive" would be used.
Also, since the pitcher was throwing what could be considered to be the final pitch of the championships, the crowd would be attentive to see what the outcome is i.e whether or not it may lead to the opposition team earning a point.
