Johnny is a forensic scientist. he tests for gunshot residue. which of the following tests might johnny use?

johnny uses the test, which should turn the material red if gunshot residue is present. for another item, he only has a small amount of material to test, so he chooses which is known to return conclusive results even on very small amounts.

a. dermal nitrate
b. sem-edx
c. griess reagent

a. dermal nitrate
b. sem-edx
c. griess reagent