Final answer:
A root CA is a trusted entity that issues digital certificates. The public key of a root CA can be obtained from the CA's official website or its authorized representatives.
Step-by-step explanation:
A root CA (Certificate Authority) is a trusted entity that issues digital certificates, which are used to verify the identity and authenticity of individuals or websites in secure communications. The public key of a root CA can be obtained in an authentic manner by downloading it from the CA's official website or obtaining it directly from the CA's authorized representatives. It is important to ensure that the website or source from which the public key is obtained is legitimate and belongs to the trusted root CA.