Sentence Correction

. Few people realize that the chance of accidental injury or death may be as great or greater in the “safety” of their own homes than in a plane or on the road.
(A) may be as great or greater in the “safety” of their own homes than
(B) is at least as great or greater in the “safety” of their own homes than
(C) might be so great or greater in the “safety” of their own home as
(D) may be at least as great in the “safety” of their own homes as
(E) can be at least so great in the “safety” of their own home as

OA - D

Please explain

one reason why D is correct - it follows idiom as ..... as