A student notices dogs have more fleas in the summer than in the winter. Based on these observations, which is the most logical question for the student to investigate?
A: How does temperature affect the amount of fleas on dogs?

A student determined the density of different bars of soap. Which should the student most likely do to check the accuracy of the results?
A: repeat the experiment

Where do plants get energy from to make food?
A: sunlight

Roger poured water over a pile of sand. Some of the sand washed away. This process is similar to which of the following?
A:
The erosion of the walls of a canyon