Computer Science for IGCSE & O level - Data Transmission (Section 12 - No. 45)

In the context of data security, what does 'non-repudiation' mean?

The ability to read the message.

The ability to prove the identity of the sender.

The sender cannot deny having sent a message.

The ability to verify the data has been modified.

Non-repudiation prevents the sender from denying that they sent the message.