As the collection of physical evidence begins
a. the police chief has primary responsibility of maintaining the chain of custody.
b. all observations should be recorded through photographs, sketches and notes.
c. the district attorney should be consulted for admissibility of physical evidence in court.
d. the medical examiner should oversee the collection of the evidence at the crime scene.

Based on the observation that only male crickets produce a song, you hypothesize that a male's song is a form of communication to potential mates. you set up a simple experiment to test this hypothesis. in the laboratory, you place a male snowy tree cricket in enclosure a, which is adjacent to enclosureb. in enclosure b, you place other insects, one at a time, and observe their responses to the male's song. the enclosures are designed so that the two insects being tested cannot see or smell each other, but sound is transmitted from enclosure a to enclosureb.