Final answer:
The correct passive voice transformation of the sentence 'Rachel made a cake yesterday' is 'A cake was made by Rachel yesterday.' This adheres to the passive voice structure using the past tense form of 'be' (was) and the past participle of the verb 'made.'
Step-by-step explanation:
The sentence Rachel made a cake yesterday is in the active voice. To transform this sentence into the passive voice, we should ensure that the subject is the recipient of the action rather than the doer. This involves using a form of the verb be plus the past participle of the main verb, and typically includes a by phrase indicating the doer of the action.
Following these guidelines, the correct transformation of the sentence into passive voice is:
- A cake was made by Rachel yesterday.
This option uses the past form of the verb 'be' (was) which corresponds to the past tense of the active sentence, and includes the doer of the action (by Rachel). Other options either use the incorrect tense of the verb 'be' or do not convert the sentence to passive voice properly. Therefore, the correct answer is option (a).