He is very meticulous in keeping accounts.

Answer: Option C

Meticulous : showing great attention to detail; very careful and precise.
Clumsy : awkward in movement or in handling things.
Irregular : not even or balanced in shape or arrangement.
Careless : not giving sufficient attention or thought to avoiding harm or errors.
Irresponsible : (of a person, attitude, or action) not showing a proper sense of responsibility.

Antonym of Meticulous is Careless