QUIESCENT

Answer: Option A

Quiescent : In a state or period of inactivity or dormancy.
Active : Ngaging or ready to engage in physically  energetic pursuits.
Dormant : Having normal physical functions suspended or slowed down for a period of time.
Weak : Lacking the power to perform physically demanding tasks.
Unconcerned : Showing a lack of worry or interest.

Antonym of Quiescent is Active.