Answer: B
Explanation: Graph B compares the two temperatures on separate lines so that we can see the comoparison directly, as a function of time. Not only does the graph quickly answer which condition id most favorable to colony growth, but it also hints at some behaviors that may accelerate growth as time goes on. Graph C is a possible answer, if the only question is which promotes growth the fastest. But the questions asks "compare," which Graph B does not allow as well as Graph C.