GMAT Sentence Correction (SC) | Re: QOTD #16 According to the Oxford dictionary, the term ‘euphemism’ refe

Hello,

Can anyone help me in understanding Missing verb error or lack of main verb for the options A &C.? As far as I have understood, the options A & C indicates to replace a mild word with a harsh word, but I couldn't get the context of missing verb error or lack of main verb.

(A) referring to the substitution of a mild word with a harsher word - Incorrect. Missing verb error.

(B) refers to the substitution of a harsh word with a milder one - Correct.

(C) which refers to the substitution