Most of the higher organisms are aerobic. Through aerobic respiration, oxidation of biomolecules happens which provides us with the maximum energy.

Statement: Animals require oxygen for aerobic respiration.

Explanation:
Animals are multicellular eukaryotic organisms that belong to the kingdom Animalia. They are heterotrophs, meaning they obtain their nutrition by consuming other organisms.

Respiration in Animals:
Animals require oxygen for a process called aerobic respiration, which is the primary method by which energy is produced in their cells. Aerobic respiration involves the breakdown of glucose (a sugar molecule) in the presence of oxygen to produce carbon dioxide, water, and energy in the form of ATP (adenosine triphosphate). This process occurs in the mitochondria of animal cells.

Importance of Oxygen:
Oxygen is crucial for the efficient functioning of animal cells. It acts as the final electron acceptor in the electron transport chain, a series of chemical reactions that occur during aerobic respiration. This electron transport chain generates a proton gradient across the inner mitochondrial membrane, which is used to produce ATP through a process called oxidative phosphorylation.

Without an adequate supply of oxygen, animals would not be able to carry out aerobic respiration efficiently. As a result, they would not be able to produce enough ATP to meet their energy requirements. This would lead to cellular dysfunction and ultimately, the death of the organism.

Other Options:
a) Animal cells possess a cell wall: This statement is false. Animal cells do not possess a cell wall. Instead, they have a flexible plasma membrane that surrounds their cells.
b) Animals are unicellular eukaryotes: This statement is false. Animals are multicellular organisms, meaning they are composed of multiple specialized cells that work together to form tissues, organs, and organ systems.
c) Animals have autotrophic nutrition: This statement is false. Animals are heterotrophs, which means they obtain their nutrition by consuming other organisms.
d) Animals require oxygen for aerobic respiration: This statement is true, as explained above.