Which sentence is punctuated correctly?

A.
Michelle Obama, who is a lawyer, has achieved much who knows what else she might accomplish?

B.
Michelle Obama, who is a lawyer, has achieved much; who knows what else she might accomplish?

C.
Michelle Obama, who is a lawyer, has achieved much, who knows what else she might accomplish?

B. Michelle Obama, who is a lawyer, has achieved much; who knows what else she might accomplish?