Concept:The fifth hadith of an-Nawawi addresses the rejection of newly introduced matters in religion.
Explanation:According to this hadith, the Prophet (peace be upon him) said that whoever introduces something new into this religion which is not part of it, that act is rejected.
This hadith specifically warns against religious innovation or bid'ah.
It does not primarily refer to anger, gossip, or theft as the main subject, although those are also forbidden in Islam.
Therefore, the prohibition in the fifth hadith is about innovation in matters of faith and worship.
Answer:B. innovation