What is the function of CAPTCHA in online security?

• A. To encrypt data in transit.
• B. To monitor user behavior for analytics.
• C. To prevent automated bots from accessing web services by requiring human verification.
• D. To enforce password changes.

Answer: (C)

CAPTCHA is built to separate humans from automated programs by presenting a challenge that is easy for people to solve but hard for bots. This lets websites block automated abuse—such as mass account creation, spam, and data scraping—while still allowing legitimate human users to access services. It’s not about encrypting data in transit (that’s what TLS/SSL does), nor is it primarily about watching user behavior for analytics (that’s separate analytics tooling), and it doesn’t enforce password changes (that’s a different security control).