Which statement is true about a cell?
a. the smallest living things are cells.
b. all known living things are made of multiple cells.
c. cells stop producing once adulthood is reached.
d. organs produce cells.

a. The smallest living things are cells.

Cell theory states that:
1. Cells came from pre-existing cells
2. Cells are the basic unit of life
3. All life is composed of cell/s

More:
The cellular organization relates with one another since the colossal cell, the organ system is fundamentally composed of cells. Cells are the building blocks of these structures and which creates such organ and organ system. They associate as one cell intercommunicates with another cell until all received the message and translates it and sends it with another organ and to cell -vice-versa. And also, they become interdependent with the other cell -other tissue -other organs -other organ system.

More; less is the correct answer