A novice rower is practicing for a 2000-meter test on a rowing machine (an “erg”). He presently takes 7 minutes and 10 seconds to complete the distance. His goal, in order to be recruited by a good college, is 6 minutes and 30 seconds. What form of improvement trajectory will most likely occur? 

a. Exponential growth 

b. Exponential decay 

c. Diminishing return growth