Here's a problem to solve: Pat has two kinds of plant food,""Quickgrow"" and ""Supergrow."" What would be the best way for Pat to find out which plant food helps a particular type of houseplant grow the most?

Among the 4 following options, which is the correct answer?

- A: Put some Quickgrow on a plant in the living room, put some Supergrow on a plant of the same type in the bedroom, and see which one grows the most.
 
- B: Find out how much each kind of plant food costs, because the more expensive kind is probably better for growing plants.
 
- C: Put some Quickgrow on a few plants, put the same amount of Supergrow on a few other plants of the same type, put all the plants in the same place, and see which group of plants grows the most.
 
- D: Look at the advertisements for Quickgrow, look at the advertisements for Supergrow, and see which one says it helps plants grow the most.
 