Select the correct answer. Fastex Shoes claims that it has designed a new range of lightweight shoes that allow athletes to run faster than they can using any other shoes. SportsPlus, a rival shoe manufacturer, then came up with a design that it claims performs even better than Fastex's design. A sports magazine decided to test the claims. It created two groups of 15 randomly selected athletes each. Members of both groups were pretested and determined to have equal athletic ability. Additionally, they followed the same nutrition plan and training program during the study.

The athletes did a 1-mile run to test the shoes. The magazine found that the athletes who used Fastex shoes had reduced their 1-mile run time by an average of 3%, and athletes who used SportsPlus shoes had reduced their 1-mile run time by an average of 2%.

Given the magazine’s data collection method and findings, what conclusion can be made?

A.
The data collection method used was random since the athletes in the two groups used two different shoe designs.
B.
The data collection method used was unfair since the athletes given Fastex shoes may have been better runners than the athletes given SportsPlus shoes.
C.
The data collection method used was fair since both shoe designs were tested on identical parameters.
D.
The data collection method used was nonrandom since the athletes using Fastex shoes may have trained better.