When Salma runs the 400-meter dash, her finishing times are normally distributed with a mean of 70 seconds and a standard deviation of 0.5 seconds. If Salma were to run 39 practice trials of the 400-meter dash, how many of those trials would be faster than 71 seconds, to the nearest whole number?
a. 0
b. 5
c. 10
d. 15
