A student hypothesized that bread mold would grow faster in a dark environment than a well-lit environment. She took four slices of bread from the same loaf, sprayed each with the same amount of water, and sealed them inside plastic bags. She kept two slices on the kitchen counter for six days. She kept the other two slices in a cardboard box inside her pantry for six days. She measured mold growth every two days. The table shows her data.

Based on the results of the experiment, how should the hypothesis be refined?

A. Bread mold cannot grow in a dark environment.
B. The rate of bread mold growth increases with exposure to light.
C. A wooden box will provide more darkness than a cardboard box.
D. The more moisture a slice of bread receives, the more mold it will support.