Greg and andrea are trying to find out how long it takes amylase, a digestive enzyme found in saliva, to break down a sample of starch. they put their sample in a beaker and covered it with their own saliva. after allowing it to sit on the lab table for 1 hour they measured the remaining surface area of the starch. what is the best way they could improve their experiment? a. take consistent amounts of their saliva samples with varying amounts of starch b. take consistent amounts of saliva samples and consistent amounts of starch c. take varying amounts of saliva samples and a consistent amount of starch d. take varying amounts of saliva samples and varying amounts of starch