A group of students is setting up a test to see whether earthworms, like those shown in the photo, prefer rough or smooth surfaces.
Which type of investigation is the group doing?

A.
Experimental

B.
Comparative

C.
Observational
A group of students is setting up a test to see whether earthworms, like those shown in the photo, prefer rough or smooth surfaces.
Which type of investigation is the group doing?

A.
Experimental

B.
Comparative

C.
Descriptive

D.
Controlled