Which of the following could not be considered a team sport? a. wrestling b. rowing c. tennis d. marathon race

Marathon race would not be considered as a team sport.

The answer you are looking for is D) marathon race. 
Hope it helped :)

The person who utilize the progression principle will keep adding the difficulty of the exercise that he's doing, while the person who does not, will only stay stagnant.  the person that utilize progression principle, will get a stronger endurance because now his body is conditioned to do harsher routines.{the answer was already on verified)