Which of the following process causes substances to move across membranes without the expenditure of cellular energy?

Explanation

The correct answer is Diffusion. Diffusion is characterized by the passive movement of molecules from an area of higher concentration to an area of lower concentration, which occurs naturally and does not require energy input from the cell. In contrast, Endocytosis and Active Transport both require energy because they involve active movement of substances against their concentration gradients. Therefore, the only process listed that matches the criteria of not using cellular energy is diffusion.