Answer: A)Website defacement
Explanation: Website defacement is the type of attack that is done on the website that works for the changing of the appearance or display of the particular site,. This is a unauthorized act that is done by the attackers or hackers to change the website and marking it with their own site.
Other given option are incorrect because they deal with display change of site rather a other types of the system attacks.Thus , the correct option is option(A).