In this English grammar question on voice, a sentence in the active voice is given about sending an email last week. Out of the four alternatives, select the option that best expresses the same idea in the passive voice: I have sent you an email last week.

Introduction / Context:
This question deals with transforming a present perfect active sentence into its passive counterpart. The original sentence states that the speaker has sent an email to "you" and mentions "last week" as the time of the action. Although in strict formal English present perfect is normally not used with a finished time expression like "last week", exam questions often focus on the mechanical change from active to passive. Your task is to select the option that preserves the original structure while correctly changing the voice.

Given Data / Assumptions:

• The verb phrase "have sent" is in the present perfect tense.
• The subject is "I" and the indirect object is "you".
• The direct object is "an email".
• The time expression "last week" indicates when the email was sent.
• The passive form must keep the same tense and include the receiver "you".

Concept / Approach:
To make a passive sentence from a present perfect active sentence, we use the pattern "has / have been + past participle". The direct object of the active sentence becomes the subject in the passive sentence. The original subject can be included at the end with "by" if it is necessary to mention the agent. The indirect object "you" normally remains after the verb phrase. Even though combining present perfect with a specific past time is not typical in careful writing, the exam expects you to focus on voice rather than time adverb usage.

Step-by-Step Solution:
First, identify "an email" as the direct object that will become the subject in the passive sentence. Second, note that "have sent" is present perfect, so the passive auxiliary must be "has been sent" because "email" is singular. Third, place the receiver "to you" after the passive verb phrase "has been sent". Fourth, add "by me" at the end to show who performed the action, keeping the agent information from the original sentence. Fifth, retain the time expression "last week" to indicate when the action took place, even though it is not ideal in formal usage.

Verification / Alternative check:
The sentence "An email has been sent to you by me last week" correctly follows the pattern of present perfect passive. The original object "an email" is now the subject, and the receiver "you" appears after the verb. The agent "me" is clearly expressed with "by me". The tense remains present perfect, matching the active "have sent". When read aloud, this sentence obviously corresponds to the original statement about an email sent last week, only with the focus shifted to the email itself.

Why Other Options Are Wrong:
Option A uses "had been done", which changes both the tense and the verb to a more awkward expression. Option B uses "has been done my me to yourself", which is ungrammatical and also replaces "email" with "emailing". Option D uses present continuous passive "is being sent" with a specific finished time "last week", which is clearly wrong. Only option C presents a recognisable passive form of "have sent" using "has been sent" and keeps the basic structure and meaning, even if the time expression is not ideal.

Common Pitfalls:
A frequent difficulty is confusion between various perfect and continuous forms in the passive voice, especially when the sentence includes an indirect object. Some learners also try to translate the sentence too literally and end up with awkward expressions like "sending of the email has been done". Others forget to keep the same tense and mistakenly change present perfect into past perfect or simple past. To avoid these issues, always identify the tense first, then apply the correct passive pattern, and only after that arrange the objects and time expressions in a natural order.

Final Answer:
The option that correctly expresses the sentence in the passive voice is: An email has been sent to you by me last week.