Dr. robins is a psychologist with an interest in photography. she wants to see if she can train people to salivate when they look at photographs. in her research, participants look at photographs of trees while lemonade crystals are placed on their tongues. the lemonade causes them to salivate. over the course of many trials, people start to salivate to the photographs alone. in this situation, the photographs serve as the:

Conditioned stimuli.

Explanation:

Over the course of many trials, people start to salivate to the photographs alone. In this situation, the photographs serve as the conditioned stimuli. Conditioning is a process that consists of learning a behavioral response to a previously neutral stimulus. The photographs were neutral stimuli before the conditioning. After several opportunities in which the photographs were paired with the saliva in their tongues, the photographs alone made them salivate.

  b.

there are isolated pockets of farming, generally around rivers and oases, which are used for irrigation.