Which statement best describes the difference between oxidative phosphorylation and substrate-level phosphorylation?

Oxidative phosphorylation occurs in the cytoplasm, while substrate-level phosphorylation occurs in the mitochondria.

Both processes occur in the cytoplasm and produce the same amount of ATP.

Substrate-level phosphorylation requires oxygen, while oxidative phosphorylation does not.

Oxidative phosphorylation uses a proton gradient, while substrate-level phosphorylation directly transfers a phosphate group.