A sentence is given in the passive voice: “The bank account belonging to the manager has been hacked.” Select the option that best expresses the same idea in active voice, using a general or unknown subject.

Introduction:
This question examines your ability to convert a sentence from passive voice to active voice while keeping the tense and meaning intact. The original sentence describes an action already completed on the manager's bank account by an unknown person. In such cases, English commonly uses someone as a vague subject when the real doer is unknown or unimportant. You must select the active form that sounds natural and correct.

Given Data / Assumptions:

- Passive sentence: The manager's bank account has been hacked. - Tense: present perfect passive (has been hacked). - The agent (person who hacked) is unknown. - Active voice must keep the present perfect aspect and the same meaning.

Concept / Approach:
To change a passive sentence into active voice, identify the object, the main verb, and the implied subject. The manager's bank account is the object that receives the action hacked. The implied doer is some unknown person. In active voice, we can use someone as a generic subject, and keep the verb in present perfect: has hacked. The correct active sentence therefore is Someone has hacked the manager's bank account. This retains both the tense and the idea that the doer is not specified.

Step-by-Step Solution:
Step 1: Identify the verb phrase in the passive sentence: has been hacked. Step 2: Convert this to active voice present perfect: has hacked. Step 3: Take the object, the manager's bank account, and move it after the verb in the active sentence. Step 4: Choose a suitable subject for the unknown hacker. The pronoun someone is standard for this purpose. Step 5: Form the active sentence: Someone has hacked the manager's bank account. Step 6: Match this with option D.

Verification / Alternative check:
Compare meaning and tense. The passive sentence focuses on the bank account and states that the hacking has already happened. The active sentence Someone has hacked the manager's bank account conveys the same situation from the perspective of the doer, still using present perfect. There is no change in time reference or in the seriousness of the event. This confirms that option D is accurate.

Why Other Options Are Wrong:
Option A, They have hacked the manager's bank account, is grammatically possible but introduces an unclear pronoun they, which is weaker than someone and less preferred in exam keys. Option B, Hacking has been done to the manager's bank account, keeps the sentence in a passive-like structure and sounds awkward. Option C, Bank's account hacking has been done of the manager, is ungrammatical and unnatural, combining words in a way that would not be used in standard English.

Common Pitfalls:
Many learners think that any vague subject such as they will work, but exam patterns usually expect clearer choices like someone or a specific noun. Another common mistake is to leave the verb partly passive, as in hacking has been done, which does not complete the change to active voice. Always remember that in active voice the verb should directly show the action, and the subject should be the doer of the action.

Final Answer:
Someone has hacked the manager's bank account. is the best active voice equivalent of the given passive sentence.