Perform symmetric and asymmetric encryption

Bob and Alice are using an asymmetric algorithm to exchange data. Which key should they send to the other party to make this possible?

Bob sends Alice his private key, and Alice sends Bob her private key.
Bob sends Alice his public key, and Alice sends Bob her public key.
Bob sends Alice his private key, and Alice sends Bob her public key.
Bob sends Alice his public key, and Alice sends Bob her private key.