Colloquialism is the form of conversation where the words used are normally not formal, more like the everyday language that one might use in his daily common conversations. Colloquialism involves the use of slang words that are not permissible to be used in formal speeches or conversations.
Based on the options given in the question, the sentence that includes colloquialism is sentence (d). It uses the word "ain't gonna" which is a more common word used for 'not going to'. It is more of a slang, simple, informal form of speech used between casual and common associates/ acquaintances. Thus the right answer is
