Final answer:
Muhammad Ali, the renowned heavyweight boxing champion, did not change his name to Cassius Clay. Joe Martin taught Cassius Clay to be an explosive boxer. Muhammad Ali was called 'the Louisville Lip' because he was from Louisville and liked to talk about himself.
Step-by-step explanation:
1. The answer that is NOT true about Muhammad Ali is A. He changed his name to Cassius Clay. Although he did change his name from Cassius Clay to Muhammad Ali after joining the Nation of Islam, this statement implies that he changed his name to Cassius Clay, which is incorrect.
2. The answer to the question 'Who taught Cassius Clay to be an explosive boxer?' would be C. Who guided Cassius Clay as a professional boxer?. Joe Martin was a police officer and boxing coach who mentored Cassius Clay in his early boxing career.
3. Muhammad Ali was called 'the Louisville Lip' because he was from Louisville and liked to talk about himself. He was known for his charismatic personality and his ability to generate interest in his matches by trash-talking his opponents.