Which of the following contains organ systems? Choose 1

organism
tissues
cell
organ

Organism

Explanation:

The other options are all smaller than an organ system.

A cell is the smallest. Many cells make a tissue, many tissues form an organ and many organs form an organ system. Many organ systems form the organism :))

answer: accepted answer: aquatic animals use the oxygen dissolved in water to carry out respiration. since the amount of dissolved oxygen in water is low as compared to the amount of oxygen in the air, therefore the rate of breathing in aquatic animals is much faster than it is in terrestrial animals.

explanation: