Determine whether the value is a parameter or statistic:
a) 20% of vehicles sold are compact cars.
b) 61.4% of all registered voters turned out for the 2016 elections.
c) Using Consumer Reports, a random sample of new cars gave an average of mpg 30.5.
d) Facebook tested the mean amount of time its users use the site each day, and they found the mean amount of time all users use the site is 80 minutes each day.