Answer:
The Answer is B. Quantitative data
Step-by-step explanation:
The testing on the golf club, determined a improvement in the driving distance and this was measured numerically and showed in form of a percentage in comparison with average measurements.
When the information is presented with numerical data support, we can say its a quantitative data, because it tells us "how much?".
When the information is presented just with adjetives, telling us about the performance its a qualitative data, because it tell us "how things happened?"
A control variable is the data that is going to modified in order to see changes is the independent variable. In this case, the control variable could be the weight of the club (assumption), and the independent variable the driving distance data(not percentage).