I would answer the question with your personal answer because currently there is not enough information to answer these questions :( if there is a article I would recommend adding that and i would be more than happy to help you in the comments :)
Answer:
a substrate control is an uncontaminated sample
Explanation:
it allows forensic scientiststo compare the two samples to better observe whether a flammable liquid is present
Answer:
option a is the correct option
