Cells are primarily composed of which substance?

The correct answer is protoplasm, which refers to the living content of a cell that is surrounded by a plasma membrane. Protoplasm is primarily composed of a mixture of cytoplasm and nucleus. It encompasses all the cellular components necessary for the cell's functionality, including organelles and the cytosol. This substance plays a crucial role in maintaining the life processes of the cell as it contains the materials needed for growth, metabolism, and reproduction. While cytoplasm is a significant part of protoplasm, protoplasm encompasses both the cytoplasm and the nucleoplasm within the nucleus.

Cytoplasm is indeed a component of protoplasm and contains organelles and the cytosol. However, it does not encompass all aspects of the cell's substance, particularly the nucleus.

Chlorophyll is a pigment found in plants that is essential for photosynthesis but does not constitute the primary composition of all cells, especially in the context of animal cells.

The cell membrane serves as a protective barrier around the cell but is not a substance that composes the interior structure; it simply encloses the protoplasm. Thus, while membranes are critical for cellular function, they do not account for what the cell is primarily made