What does crenation refer to in animal cells?

Crenation in animal cells describes a specific response to changes in the surrounding osmotic environment. When animal cells are placed in a hypertonic solution, which has a higher concentration of solutes than the cell's internal environment, water moves out of the cells by osmosis. This loss of water leads to a decrease in cell volume and causes the cells to shrink.

The term "crenation" is derived from the Latin word "crenare," which means to notch or indent, and this term aptly describes the notched appearance of the cell membrane as it shrinks. The process does not involve swelling or bursting, as those would occur in hypotonic environments, where water moves into the cells. Therefore, the correct option accurately captures the physiological response of animal cells to a hypertonic solution, illustrating the importance of osmotic balance in cellular health.