Of these four options, the third and the fourth ones are valid solutions.
The first one doesn't work because an eavesdropper could use Alice's public key
to decrypt the first part of this message and read the message.
The second one isn't possible because Alice doesn't have Bob's private key.
For the third one, only Bob can decrypt the entire message with his private key
and then he can use Alice's public key to get the message and verify that it came from Alice.
For the fourth option, any eavesdropper can reverse the first encryption using Alice's public key,
but cannot decrypt the full message without Bob's private key.
So both of these will work.
