B. animals
Plants have cell walls, bacteria are unicellular and fungi have cell walls too
The correct option is 3.
Enzymes are biological catalysts which speed up the rate of biochemical reactions inside the cells. Enzymes are very specific in action and they require specific conditions called optimum conditions for them to function optimally.
When the optimum conditions are not met, an enzyme's activity will be lowered or totally stopped.
Conditions that affect the optimum activity of an enzyme include: temperature, pH level and regulatory activity of regulatory enzymes and hormones.
The obligate aerobes need oxygen for their survival, while the obligate anaerobes do not. The obligate aerobes are the species that attain the energy for the process of aerobic respiration with the help of oxygen as the ultimate electron acceptor for the electron transport chain.
On the other hand, obligate anaerobes are the species, which get poisoned by the usual levels of atmospheric oxygen, and thus, get killed in the existence of oxygen.
