Bombast is when high sounding words for effect, not suitability, are used.

A. is when high sounding words for effect, not suitability, are used.
B. is the use of high-sounding words for effect rather than for suitability.
C. is where high-sounding words are used for effect not suitability.
D. is the using of high-sounding words for effect only.
E. is when you use high-sounding words for effect rather than for suitability.

What's wrong with options C and D? Can any experts help?