Final answer:
Methanotrophs are the group of bacteria that use CH₄ as an electron donor and O₂ as an electron acceptor during cellular respiration.
Step-by-step explanation:
The group of bacteria that uses CH₄ as an electron donor and O₂ as an electron acceptor during cellular respiration is known as methanotrophs. Unlike methanogens, which produce methane, methanotrophs oxidize methane, utilizing it as their source of electrons in their energy-producing reactions. Methanotrophs play a crucial role in the carbon cycle by consuming methane, a potent greenhouse gas.