Context: Eric is painting watercolor pictures with his friend. An hour after they have finished, Eric notices one painting is dry but the other is not. He wonders what factors affect how quickly watercolor paintings dry. So, he decides to design an experiment. He has the following supplies available:
two freshly painted watercolor pictures of the same size
his dining room table
a picnic table in his backyard
a heater
Using only these supplies, which question can Eric investigate with an experiment?
A. Do watercolor paintings dry faster when placed next to a fan?
B. Does a large watercolor painting or a small watercolor painting dry faster?
C. Do watercolor paintings dry faster when they are placed inside or outside?
Select the correct answer from the given choices and respond with the letter of the chosen option.

C