C. An apple was given to Mark by Sandra.
Feedback Sometimes we need to change a sentence from the Active voice into the Passive voice. We can also know a person who carries out the action. In this case we form a sentence according to this word order: Subject - Be+ Past Participle - Preposition 'BY' - Agent (who or what carries out the action). Here the Past Simple Passive should be used: was given. Other answers are illogical.