Which of these is NOT a marketing call to action?

Testing two different Calls to Action to see which perform better is called:

What is niche marketing?

What is a floating ad?

Often referred to simply as Blogger, which is Google's blogging platform?

What type of marketing is blogging considered to be?

What is meant by 'niche marketing'?

Why is reciprocal linking becoming an important way to reach potential clients?

What is the 'active voice' style of writing ads?

What is A/B testing?

Why is the subject line of any email campaign important?