c) 1 in 16
When flipping a fair coin, the probability of getting tails on a single flip is 1/2. To find the probability of getting tails four times in a row, you multiply the probability by itself four times: (1/2) * (1/2) * (1/2) * (1/2) = 1/16. Therefore, the correct answer is c) 1 in 16.
