The probability that a bulb produced in a plant is defective is 0.02. If the bulb is defective, the probability that it fails within the first 100 hours is 0.80; if it is not defective, this probability is 0.05. Calculate the probability that a randomly chosen bulb fails within the first 100 hours.
a) 0.016
b) 0.066
c) 0.065
d) 0.049