Which is an example of class evidence?

a. the scientist excludes a suspect from a crime investigation after analyzing fingerprints on the murder weapon and those of the suspect.

b. the scientist reports that kerosene from acme organic products was the accelerant used in an arson.

c. the scientist establishes that the dna from an assault suspect was found on the victim.

d. the scientist matches the toolmark on a broken door in a burglary with a toolmark made from a crowbar in a suspect's car.