(C) Spinal cord

Vertebrae are part of the spinal column, also known as the backbone or spine. The spinal column is a bony structure that encases and protects the spinal cord, which is a crucial component of the central nervous system. The spinal cord is responsible for transmitting signals between the brain and the rest of the body, allowing for communication and coordination of various bodily functions.

Answer: C) unicellular Explanation: An organism is a living thing, and there are two broad categories of organisms: those made up of only a single cell, and those made up of multiple cells. Single-celled organisms means which contains only one cell are called unicellular organisms. 'Uni-' means 'one,' so the name 'unicellular' literally means 'one cell.'   Examples of Unicellular or Single celled organisms ::   Prokaryotic organisms like Bacteria,... Some algae like green algae, euglena,...