Conversation so far:
Where was Muhammad Ali born?
Muhammad Ali was born in Louisville, Kentucky.
When was Muhammad Ali born?
Muhammad Ali was born on January 17, 1942.
What did Muhammad Ali's parents do for a living?
Muhammad Ali's father, Cassius Marcellus Clay Sr, was a sign and billboard painter.

Question: Who was his mother?
Self-contained rewrite: Who was Muhammad Ali's mother?