What does the pulmonary artery do?

Look at the following answer choices and determine which belongs in the both category. testable, can be disproven explains natural phenomena, has evidence to support it prediction, tentative, one or more scientists working together well established, many different scientists working independently, highly reliable

Depending on the organism the number of in a cell may change

What are the doorways into and out of cells, attached to the membrane, and built in the rough er.