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

One should not give unasked advice.

 Unasked advice should not be given.

Unasked advice should not be given.

Explanation:

• Unasked advice is not to be given.: This passive construction changes the meaning slightly by using "is not to be" instead of "should not be."
• Unasked advice can't be given.: This passive construction changes the meaning slightly by using "can't be" instead of "should not be."
• Unasked advice may not be given.: This passive construction changes the meaning slightly by using "may not be" instead of "should not be."
• Unasked advice should not be given.: This construction correctly maintains the original meaning and reverses the subject and object while using the appropriate verb tense.