He is quite meticulous in his dealings with others.

Answer: Option D

Reserved : slow to reveal emotion or opinions.
Haughty : arrogantly superior and disdainful.
Indifferent : having no particular interest or sympathy; unconcerned.
Careful : making sure of avoiding potential danger, mishap, or harm; cautious.
Meticulous : showing great attention to detail; very careful and precise.

Synonym of Meticulous is Careful