Final answer:
Pinocytosis is the process of a cell taking in small particles dissolved in fluid from the extracellular fluid.
Step-by-step explanation:
When droplets of fluid are taken into a cell, the process is known as pinocytosis. Pinocytosis is a form of endocytosis, which is the process of a cell ingesting material by enveloping it in a portion of its cell membrane and forming a vesicle. In pinocytosis, the cell takes in small particles dissolved in fluid from the extracellular fluid.