Answer: 3. C. mitochondrion
Explanation:
Mitochondrion in a cell is defined as the powerhouse of the cell which provide energy to the whole cell.
A mitochondrion is has a membranous layer and bean-shaped organelle that is the “energy transformer” of the cell. They contibute to the biochemical processes of the cell called cellular respiration. They works as a digestive system which takes nutrients, breaks them into several energy rich molecules for the cell.
Hence, the correct answer is 3. C. "mitochondrion".
The cell membrane functions as a selective barrier. We call these kind of membranes as differentially permeable or semi permeable membrane. It can decide what substances can pass in and out. Therefore it can surround the cytoplasm (which is the inside of a cell) to separate the cell's content from the surroundings.