Step 1: Meaning of the lines: The poet says that when he went out to look for a bad person, he found none. Step 2: When he searched his own heart, he found that no one was worse than himself. Step 3: So the poet teaches self-examination: improve yourself first instead of pointing at others. Step 4: The other options contradict the couplet or are never stated in it. Answer: We should first look at our own faults before blaming others.