He exhibited a comprehensive approach towards the matter in hand.

The correct answer is C. exhaustive.

A comprehensive approach is one that is thorough and complete. It takes into account all aspects of a problem or situation. A slipshod approach is careless and incomplete. A sketchy approach is superficial and does not provide enough detail. A superficial approach is also not thorough and does not consider all aspects of a problem or situation.

In this case, the speaker is