QUERULOUS:

A. Disconnected

B. Timorous

C. Disputed

D. Contented

Answer: Option D

Solution(By Examveda Team)

Disconnected: Having connection broken, detached, Not connected, lacking contact .
Timorous : Nervousness or a lack of confidence.
Disputed: Disagreed, Argued
Contented : Feeling happiness or satisfaction.
QUERULOUS: Complaining or petulant, Argument.

Antonym of QUERULOUS is Contented .