What limitation do electronic detectors have in fire investigations?

The correct answer highlights a key limitation of electronic detectors used in fire investigations, which is their inability to differentiate between ignitable liquid residues (ISRs) and pyrolyzed debris. This means that while these detectors can identify the presence of certain chemicals indicative of accelerants (such as gasoline or lighter fluid), they cannot always distinguish whether the source of those chemicals is an accelerant or the remnants of organic materials that have undergone pyrolysis due to heat exposure during a fire.

When a fire occurs, materials can break down and produce a variety of byproducts, many of which can resemble the signatures of accelerants detected by the device. Therefore, when interpreting results from electronic detectors, investigators must exercise caution and consider additional evidence to ascertain whether an ignitable liquid was indeed used. This emphasizes the complexity of fire investigations and the need for careful analysis when relying solely on electronic detection methods.

The other options present limitations that do not accurately represent the functions of these detectors. For example, they can work in low-light conditions, they are capable of detecting chemicals in various forms (not just solids), and they can be effectively used in outdoor settings, making those aspects less relevant to the limitations that electronic detectors face in this context.