Which of these statements expresses a scientific theory? O A. Any cell that contains a nucleus is usually larger than any cell
without a nucleus
O B. A material that consists of one or more cells is a living organism.
O c. All living organisms have a body that consists of one or more
cells.
O D. A study of material found on a beach showed the presence of
cells.

The cell is the basic structural and functional unit of living organisms

Explanation:

before, trains worked using the steam engine. thus, it uses heat so it is crucial to apply heat balance. the steam engine absorbs energy during the stage of boiling water. so, this is the endothermic reaction. when the steam is used to work the piston, it has to release this energy through running the train. the excess energy is released as an exhaust to the chimney. this is the exothermic process because it releases energy to the surroundings.