Regular aerobic exercise gives an individual more endurance is a sentence that shows cause and effect. which word indicates the cause?
a. individual
b. exercise
c. endurance
d. regular

b. Exercise

If we conduct a research investigation in these given situation. More specifically, an experiment this would suggest a most probable scenario of a cause and effect situation or technically called causality. 

Here the Independent variable is the exercise 
The dependent variable is the endurance.

Hence regular EXERCISE increases endurance.