The protein rods of the cell's cytoskeleton that function in muscle contractions, cleave furrow formation, and amoeboid movement of the cell are _______.

A. Addition of a water molecule between each two units: Adding water breaks bonds during hydrolysis, so this process does not synthesize carbohydrates or proteins but rather breaks them down.

B. Removal of a carbon atom between each two units: Synthesis does not involve removing carbon atoms. The carbon skeleton of monomers remains intact when forming polymers.

C. Removal of a water molecule between each two units: Condensation (or dehydration) reactions synthesize carbohydrates and proteins by linking monomers. Each bond formation releases a water molecule, connecting sugars into polysaccharides or amino acids into polypeptides.

D. Addition of a carbon atom between each two units: Carbon atoms are not added during polymerization; the existing carbon atoms in monomers are used to form the polymer chain.

A. Diaphragm: The diaphragm is a dome-shaped sheet of muscle that physically separates the thoracic cavity from the abdominopelvic cavity. It also plays a key role in breathing by contracting and relaxing to change thoracic volume during respiration.

B. Liver: The liver is a large organ located in the upper right portion of the abdominal cavity. While it sits just below the diaphragm, it does not form a dividing structure between the thoracic and abdominopelvic cavities.

C. Pelvis: The pelvis forms the lower part of the trunk, providing structural support and housing parts of the urinary and reproductive systems. It does not serve as a boundary between the thoracic and abdominopelvic cavities.

D. Colon: The colon is part of the large intestine that runs within the abdominopelvic cavity. It does not have any structural role in separating body cavities, as it is entirely contained within the lower cavity.