Ms. Fleming's class sets up an experiment involving pendulums. You can see in the picture that a pendulum is a "bob" attached to a string which hangs from a fixed point, allowing the bob to swing back and forth. They hook a 10 gram bob to a 12 inch string, and measure the time it takes for the bob to swing back and forth one time as 2 seconds.
Then the class hooks a 20 gram bob to a 20 inch string and measure the time it takes to swing back and forth as 4 seconds.
Erin hypothesizes that the difference in time is related to the type of string used. What would NOT be a good alternative explanation?

A) That the difference is due to the different masses
B) That the difference is linked to the length of the string
C) That the difference is due to the temperature of the bobs