Correct Answer: D
Explanation:
Imperative sentences denoting suggestion or advice follow below rule.
Active – V₁ (Ist from) + Object
Passive – Object + should + be + V₃ (III form)
Now, the statement given in the question is a general case of morality.
Therefore, no need to write (by + agent or subject) as it is already obvious.
Hence, option D is the correct answer.