Final answer:
Spammers can defeat the registration process of free e-mail services by launching coordinated bot attacks that can sign up for thousands of untraceable e-mail accounts.
Step-by-step explanation:
The subject of this question is Computers and Technology. The student is asking about the method used by spammers to defeat the registration process of free e-mail services and sign up for multiple untraceable e-mail accounts. The correct answer is b. bot.
Spammers use automated programs known as bots to launch coordinated attacks on the registration process. These bots can quickly sign up for thousands of accounts without being traced back to the spammers. It allows them to bypass security measures like CAPTCHA, which are designed to prevent automated sign-ups.
By using bots, spammers can flood the free e-mail services with their accounts, making it difficult for legitimate users to sign up and creating opportunities for spam and other malicious activities.