From link in nascarnation’s post:
” What specific questions are asked on the 2015 National Content Test?
For each household, we will ask how many people live in the house, and for each person we will ask the name, sex, age, relationship, and race/origin. We also will ask whether the housing unit is owned or rented, the telephone number, and an email address. Some people will receive different versions of question wording because studying the effectiveness of different content is a part of the test.
(FAQ12408)
Do I have to respond to the 2015 National Content Test?
Yes. Participation in the test is mandated by law (Title 13 of the U.S. Code). This same law also requires the Census Bureau to keep your answers confidential and allows them to be used only to produce statistical summary data. In other words, the Census Bureau does not publish data that would identify individuals.
(FAQ12418)