For a study to accurately reflect a target population behavior, it must use measures.
a. both reliable and valid
b. only reliable
c. only valid
d. neither reliable nor valid

a. both reliable and valid

The parameters used to describe a particular trait or characteristic in a human behavior should be reliable and valid, in order to determine the response of the population with respect to a particular stimulus.

explanation: look here

the earths atmosphere is made up of nitrogen and oxygen. solids can turn into gasses through a process called sublimation. sublimation is the transition of a substance directly from the solid to the gas phase, without passing through the intermediate liquid phase.

hope this : d