A sentence is in active voice when the subject is the doer of the action.
A sentence is in passive voice when the new subject (object in active voice) is the receiver of that action.
The given sentence: "Fred ___ to see the cold response of Mr. Scrooge..." requires a verb in passive voice form.
Option C: 'Was shocked' is in simple past tense (passive voice). It's the most suitable option, as the subject "Fred" receives the action "was shocked". Hence C is correct.
Option A: 'Shocked' is in the simple past tense, but in the active voice. Hence A is incorrect.
Option B: 'Been shocked' is incomplete on its own. The auxiliary verb 'had' is essential for this tense form (past perfect continuous tense: had + been + past participle). Hence B is incorrect.
Option D: 'Being' is a participle, which is used in the past continuous tense (passive): was/were being. It does not combine with the auxiliary 'had'. Hence D is incorrect.