There are two groups of earthworms on the sidewalk. One group is on a shady, moist area on the sidewalk, and they are moving. The other group is on a very sunny, dry area of the sidewalk, and none of the worms in this group are still living.
What question could be asked to investigate the reason for these observations?
A. What kind of living environment do earthworms need?
B. How do earthworms get on the sidewalk?
C. Why do earthworms crawl?
D. What kinds of birds eat earthworms?