Answer: unbiased; simple random sampling
Step-by-step explanation:
From the question, we are informed that John wanted to know about the popularity of a particular movie and that he surveyed 20% of the people in 5 different theaters.
This is an unbiased sample. This is because everybody at the theaters have an equal chance of being chosen by John.
Also, it's a simple random sampling. This is because a subset of the entire population is randomly selected.
