Which changing external condition triggers the salivary glands?

a. lack of oxygen

b. lack of water

c. disease-causing agents

d. change in temperature

The correct answer is B. Lack of water. When there's no water and you start to dehydrate, your salivary glands start working extra hard because your mouth can't be dry and the salivary glands produce saliva to keep the mouth and the throat dry. If your throat and mouth are dry you can't even swallow.