The deep scattering layer (DSL): a) was discovered by Charles Darwin
b) is only seen at night
c) is a biological phenomenon that can be detected with sonar
d) is not a biological phenomenon
e) is a chemical boundary in the water

Jenny wants to test the electrical conductivity of two substances dissolved in water. she is preparing the containers for the experiment. which factor is most important for her to control? a) volumes of the solutions b) appearance of the solutions c) temperatures of the solutions d) concentrations of the solutions