Final answer:
A man-in-the-middle attack involves a hacker intercepting and possibly altering communications between two parties by impersonating one of the entities involved in the communication.
Step-by-step explanation:
A man-in-the-middle attack (MITM) occurs when a hacker inserts themselves into a communication session between two parties to intercept, and possibly alter, the information being exchanged. This type of attack is a significant security concern because it can be used to steal sensitive data, such as login credentials and credit card numbers. The most accurate description of a man-in-the-middle attack from the provided options is when a false server intercepts communications from a client by impersonating the intended server. Hackers use various methods during this attack, such as ARP poisoning, DNS spoofing, or using SSL/TLS vulnerabilities to deceive and exploit their targets.