Answer:
a. They are the most basic unit of life which make up organisms
Explanation:
Cell is the smallest basic structural and functional unit of the living being, being considered the smallest portion of a living matter.
The cells were discovered in 1665 by the English mathematician Robert Hooke, who observed cork cells through the microscope. It was he who gave the name "cell", from the Latin cella = small cavity, compartment or part of a house.
The cells are surrounded by a cell membrane and filled with a concentrated aqueous solution of chemicals called cytoplasm, where scattered organelles are found.
In some multicellular beings cells organize and form tissues, which are sets of cells that act in coordination to perform a certain function. Tissues, in turn, cluster and form the organs that make up the systems (digestive, nervous, respiratory, circulatory).
