subject- cryptography/security engineering

Which one of these statements is correct about a Public-key cryptosystem?

Select one:

a.

It provide data integrity as well, because a modified ciphertext will not get decrypted.

b.

After generating a private-public key pair, the public key should be published, and the private key should be immediately destroyed for better security. It can be always derived from the public key whenever required.

c.

It should not be computationally feasible to compute the public key by knowing the private key.

d.

It does not provide any guarantee that a ciphertext coming from Alice is really produced by Alice.

e.

A given public key may produce the same ciphertext for two different plaintexts.