The answer is to improve efficiency.
If message m is very long, RSA could be a very expensive operation,
so we only want to run the encryption on the hashed message,
which wold be smaller.
The first option is not true.
The security of this scheme depends on the encryption function, not on the hash function.
The third option is not true.
Asymmetric decryption is necessary in both schemes.
The fourth option is not true, because we haven't done anything to increase the message space.
