The answer to your question is The grade of a metric bolt is designated by the number stamped on the head of the bolt.
Answer:
b. Certificate Authority
Explanation:
Based on the information provided within the question it can be said that they are communicating with each other by using a certificate authority. This term refers to a company or organization that provides security verification by issuing both parties cryptographic keys which are specifically verified by the company in order to allow both parties to know exactly who they are communicating with.
