For the following scenarios, determine whether or not they represent paired designs.
a. Reaction times for students taken at 8:00 a.m. compared to reaction times for the same students taken at 10:00 p.m.

b. Change in weight for those on the Atkins diet compared to the change in weight for those on the Paleo diet.
c. Times for skiers to complete a downhill skiing race course on skis treated with Wax A with times for the same skiers to complete the course on skis treated with Wax B.