Context: The passage below describes an experiment. Read the passage and then follow the instructions below.

Isabelle prepared ten buckets, each with one gallon of boiling water and three tablespoons of black fabric dye. Isabelle soaked white linen fabric squares in five of the buckets, and white cotton fabric squares in the other five buckets. All of the fabric squares were soaked for 15 minutes. After the fabric dried, Isabelle scored the darkness of the squares on a scale from light to dark. She compared the darkness of the linen fabric to the darkness of the cotton fabric.
Figure: fabric that has been dyed black.
Identify the question that Isabelle's experiment can best answer.
A. Does fabric turn darker when soaked in a mixture of black dye and water for 15 minutes compared to 30 minutes?
B. Does linen fabric turn darker than cotton fabric when soaked in a mixture of black dye and water?
From the given choices, choose the correct answer and respond with the letter of that choice.

B