Context: Katy is burning some new candles. She notices that they produce different amounts of smoke. She wonders what factors affect how much smoke a candle produces. So, she decides to design an experiment. She has the following supplies available:
two large unscented candles with thick wicks
two large unscented candles with thin wicks
a box of matches
Using only these supplies, which question can Katy investigate with an experiment?
A. Do candles with thick wicks or with thin wicks produce more smoke?
B. Do scented candles or unscented candles produce more smoke?
C. Do large candles or small candles produce more smoke?
Select the correct answer from the provided options and reply with the letter associated with it.

A