Brute force protection will:

Brute force protection monitors authentication events and enforces an account lockout or temporary block once a defined threshold of unsuccessful login attempts is exceeded, directly countering automated password-guessing attacks. This is the canonical definition of the feature across web application firewalls, identity platforms, and application security frameworks.

Blocking based on the number of page requests describes HTTP rate limiting or request throttling, which is a separate control unrelated to authentication failure counting.

None of the above is incorrect because option A accurately and completely defines brute force protection.

Restricting content downloads describes bandwidth throttling or data-transfer limits, which is a distinct control with no connection to login attempt monitoring.