What input validation method ensures that specific input rules are followed?

The correct choice is the format check, as this method specifically addresses the adherence to a predetermined structure or pattern for input data. By applying format checks, a program can ensure that inputs conform to expected types, such as dates, phone numbers, email addresses, or specific string patterns. For example, a format check might verify that a phone number consists of exactly ten digits or that an email address contains an "@" symbol followed by a domain name.

In the context of software development and data entry, employing format checks is crucial for data integrity, as it prevents users from entering information that does not conform to established standards, thereby reducing errors and ensuring that the input can be processed correctly by the system.