He was dismissed from service because they found him dishonest.

Answer: Option B

Prevented : keep (something) from happening.
Removed : take (something) away or off from the position occupied.
Retired : having left one's job and ceased to work.
Stopped : (of an event, action, or process) come to an end; cease to happen.
Dismissed : remove from employment or office, typically on the grounds of unsatisfactory performance.

Synonym of Dismissed is Removed