Ski resorts are interested in the mean age that children take their first ski and snowboard lessons. They need this information to plan their ski classes optimally. Define the following in terms of the study. Give examples where appropriate. The sample:

a. The sample is all of the people taking skiing or snowboarding lessons.
b. The sample is all of the children taking skiing or snowboarding lessons.
c. The sample is a group of the people taking skiing or snowboarding lessons.
d. The sample is a group of the children taking skiing or snowboarding lessons.