_______________ is called the living substance of the cells

Protoplasm is called a living substance of the cell.

Protoplasm = Cytoplasm + Nucleus

Protoplasm is the colourless material comprising the living part of a cell, including the cytoplasm, nucleus, and other organelles.

The cytoplasm, the cell organelles and the nucleus are enclosed within the cell membrane.

Cytoplasm is a gel-like fluid that fills each cell and is enclosed by the cell membrane.

The cell membrane is found in all cells and separates the interior of the cell from the outside environment and it is also known as the plasma membrane.

A cell wall is defined as the non-living component, covering the outermost layer of a cell.

Hence, the correct option is A: i.e., Protoplasm