Parietal cells of the stomach produce
a. mucin
b. pepsinogen
c. hydrochloric acid
d. rennin

The phlogiston theory in the 17th century attempted to explain burning. the theory stated that combustable objects contained a material called phlogiston, a substance without mass, color, odor, etc. after objects burned, the objects were dephlogistonated and were then in their true form. the phlogiston theory was accepted until the 18th century, when lavoisier proved that combustion requires a gas that has mass. phlogiston is considered a) to be scientific knowledge b) not to be scientific knowledge c) to be proven by scientific method d) to be accepted in the modern scientific community

Which of the following is not a food produced in rainforests? a) coffee b) cocoa c) avocados d) wheat

The response is the basis for vaccination. primary secondary tertiary none of the above