Sentence Correction

If the new airboat does what it is to be doing—

travel at high speeds undeterred by sandbars,

crocodile-infested mudflats, or marshy hippo

haunts—it could revolutionize transport on the

2,900-mile-long Congo River.



(A) If the new airboat does what it is to be doing

(B) If the new airboat does what it is supposed to do

(C) If it does as the new airboat is supposed to do

(D) Doing what it is the new airboat is supposed

to do

(E) Doing what the new airboat is to be doing

A) usage of "doing" with respect to "travel" seems unparallel. Also "what it is to be doing" is awkward

B) correct. supposed to is the right idiom
C) changes the subject
D) awkward
E) usage of "doing"

my ans is B

whts the OA?

my answer is B, too.