physical, buttwheat. magnetic attraction/repulsion isn't a REACTION; it's just a physical manifestation of polarized electron spin. also, for the DUH part, magnetism (and e-fields) is considered a part of PHYSICS, not CHEMISTRY. stop reading the qu'ran and pick up a science book, abdul!
It's a CHEMISTRY class. The whole question is that you're filtering sand, nails, and salt and you're using a magnet, filter screen, and water so you have these choices in what kind of reactions you're using:
A. just physical reactions/processes.
B. just chemical reactions/processes.
C. both chemical and physical reactions/processes.
D. forgot what this said.
I said C and apparently it's wrong. I don't kow how I didn't know that.