To effectively protect your online accounts from unauthorized access, even if your password is stolen, what cybersecurity measure is considered *most effective*?
A) Using a very long and complex password that includes special characters.
B) Regularly changing your password every few months.
C) Enabling two-factor authentication (2FA) for all your critical accounts.
D) Only accessing your accounts from private, secured Wi-Fi networks.
E) Avoiding clicking on any links in emails, regardless of the sender.