Hey we need more info to answer this question.
The correct answer to "Nine out of ten Americans already file their taxes on the Internet. What are you waiting for?" is:
It is a type of Bandwagon fallacy.
The bandwagon fallacy is a fallacy based on the statement that the opinion of the majority is always valid, as if everybody does it, you should do it too.
Comes from latin<em> Argumentum ad populum </em>which literally means "appeal to the people".
Effect, principal, stationery, practice, advice, new
Hope this helps!