A novice rower is practicing for a $2000-$meter tesst 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 grown