Answer:
C) a positive correlation
Explanation:
More people ⇒ Longer time is a positive correlation between those variables. However, longer time is not the desired outcome.
Rather, shorter time is the desired outcome. The correlation between more people and shorter time is negative. In order to compute that correlation numerically, one would have to define a function that would give a numerical value for "shorter time" that would model the goodness of outcome as time gets shorter.