He exhibited a comprehensive approach towards the matter in hand.

Answer: Option D

Authentic : of undisputed origin and not a copy; genuine.
Slipshod : characterized by a lack of care, thought, or organization.
Sketchy : not thorough or detailed.
Exhaustive : including or considering all elements or aspects; fully comprehensive.
Superficial : appearing to be true or real only until examined more closely.

Antonym of Authentic is Superficial