What Web browser-based security vulnerability was exploited to compromise the user?

While performing online banking using a Web browser, a user receives an email that contains a link to an

interesting Website. When the user click son the link, another Web browser session starts and displays

a video of cats playing a piano. The next business day, the user receives what looks like an email from

his bank, indicating that his bank account has been accessed from a foreign country. The email asks the

user to call his bank and verify the authorization of a funds transfer that took place.

What Web browser-based security vulnerability was exploited to compromise the user?
A . Cross-Site Request Forgery
B . Cross-Site Scripting
C . Clickjacking
D . Web form input validation