You Want to Test People's Cola Preference, So You Conduct

You want to test people's cola preference, so you conduct a taste test using two different brands of cola. However, you are worried about possible clues you may give people taking the test. So, you label the two colas and have your assistant, who does not know which cola is which, administer the test to the subjects. Thus, you have prevented yourself and your assistant from giving out any clues by using

A) random selection.
B) random assignment.
C) a single-blind experiment.
D) a double-blind experiment.