Abenefit of ipsec is
1. that it is below the transport layer and transparent to applications
2. there is no need to revoke keying material when users leave the organization
3. it can provide security for individual users if needed
4. all of the above

Option (4) is correct answer

Explanation:

IPsec stands for Internet protocol security. It is a protocol that works between two communication points. It provides integrity, confidentiality and data authentication for any network. It is used for Virtual private network.  There are two types of VPN, From which an organization needs to choose one.

IPsec and OpenSSl in which IPsec VPN uses IP security.

Benefits of this network are as follows--

Hence option D (all of the above ) are correct.

answer(a) occurs after your prediction;