Concept:The weakest level of faith is mentioned in Hadith 34 of an-Nawawi.Explanation:Hadith 34 says that whoever sees an evil should change it with his hand.If he cannot do so, then he should change it with his tongue.If he cannot do that, then he should change it with his heart.Changing an evil with the heart is the weakest of faith.So, the weakest faith is shown by changing an evil with the heart.Answer:A. heart