What is the thing called that mystery solvers use to spray around for fingerprints called?
and what is that duster they use called?

Hello, Fingerprint powders are fine powders used in dusting for fingerprints by crime scene investigators and others in law enforcement. Fingerprint powder is a very fine powder that is either white or black. White powder is used to dust prints on dark surfaces, and dark powder is used if the print is left on light colored surfaces. Officials use either talcum-based powders for white, or graphite-based powders for black. Have a Great Day!

well, that's easy; the answer's c, "it reduces contamination of the water and substrate of the estuary."