Suppose you're studying levels of job stress and measures of job efficiency in a nursing home. which one of the following statements best represents a data comparison that demonstrates a positive correlation?
a- as job efficiency increases, stress levels decline.
b- as stress levels increase, job efficiency declines.
c- as job efficiency decreases, stress levels increase.
d-as stress levels increase, job efficiency increases.

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.