Which of the Following Is an Example of Advocacy Research

Which of the following is an example of advocacy research?

A) A firm manipulates research questions to portray a favorable impression of its products.
B) A website employs people to click on its ads in order to generate increased revenue.
C) A firm surveys its existing customers in order to find those who might be interested in a new product.
D) An airline offers reduced fares to frequent fliers, but does not advertise these on its website.
E) A marketer contacts people for a survey, but is actually trying to sell a product.