A sentence has been given in Active Voice. Out of the four alternatives suggested, select the one which best expresses the same in Passive Voice.

'The police is unduly harassing me'.

I am being unduly harassed by the police.

the sentence that best expresses the given sentence in Passive Voice is: I am being unduly harassed by the police.

Here's why the other options are not suitable:

• I have been harassed: This implies the harassment occurred in the past and is completely finished, which is not the intended meaning.
• I have being unduly harassed by the police: This is grammatically incorrect. The present continuous perfect "have been being" is not a valid tense in English.
• I am unduly harassed: This uses the present simple tense, which does not convey the ongoing nature of the harassment as implied in the active voice sentence.

Therefore, "I am being unduly harassed by the police" accurately reflects the continuous present situation of being harassed by the police, making it the best choice for the passive voice version of the given sentence.