Question

Which are "c" prepositions

A. cause, center
B. can, could
C. concerning, contrary to
D. cook, cookies, cans

Answer 1

in A, there is a verb: cause, so not a good answer!
in B, can is a verb, also not,

in D cook is a verb:

so now we are left with the option C which has only prepositions: this is the right answer!