Fill in the blanks: All life begins with a single _________.

The correct option is C

Cell

The correct option is C.

The explanation for the correct option:

1. Every living organism's life begins with a single cell.
2. For example, a mango tree's existence began with a mango seed.
3. The mango seed contained an embryo, which began as a single cell in the ovary of the parent mango tree's bloom.

The explanation for the incorrect options:

Option A

1. The group of tissues forms the organ system of the body.
2. It performs different physiological functions of the body.
3. Examples of organ systems are the digestive system, circulatory system, nervous system, etc.

Option B

1. Tissue is the aggregation of cells.
2. They are formed of similar kinds of cells to perform specific functions in the body.
3. In animals, four types of tissues are present such as epithelial tissue, connective tissue, nervous tissue, and muscular tissue.

Final answer: All life begins with a single cell.