Which of these is an example of a non-random sample?
A.
Sunbathers at a free suntan lotion booth on a popular beach were asked about their favorite suntan lotion.

B.
At a free concert on the beach, five people are chosen to receive free music downloads.

C.
Twenty customers at a theme park are chosen to receive one free admission on the next visit.

D.
People on a beach boardwalk are surveyed to determine if they have a full-time job.