How many keypairs are needed for four individuals to securely communicate using asymmetric encryption?

In asymmetric encryption, each individual requires a unique keypair consisting of a public key and a private key. This mechanism allows for secure communication where one person can encrypt data using the other person's public key, and only the intended recipient can decrypt it using their private key.

For four individuals to communicate securely with one another, each individual must possess their own keypair. Therefore, when calculating the number of keypairs needed for four individuals, we simply multiply the number of individuals by the keypairs required per individual. Each of the four individuals requires one keypair, leading to a total of four keypairs needed.

The other choices do not adequately represent the number of keypairs needed for secure communication among four individuals; they either underestimate or overestimate the requirement by not accounting for the necessity of a unique keypair for each participant. Thus, the correct understanding is that each of the four individuals requires one keypair, resulting in a total of four keypairs.