Concept:The diaphragm is the primary breathing muscle that separates the chest and abdominal cavities.
Explanation:Option A is correct because the diaphragm is a dome-shaped sheet that separates the thorax from the abdomen.
Option B is correct because the diaphragm is a thick, strong layer of skeletal muscle.
Option C is not correct because the diaphragm is not made of epithelial cells.
Instead, it is composed mainly of muscle tissue and connective tissue.
Epithelial cells line surfaces, but they do not form the thick muscular diaphragm.
Option D is correct because the diaphragm plays an essential role in human respiration.
It contracts and flattens during inhalation and relaxes during exhalation.
Therefore, the only incorrect statement is C.
Answer:Option C is the statement that is not correct.