Rank the maintenance rates from lowest to highest among giant dogs, adult cats, horses/cows, and small dogs.

• A. Giant dogs, adult cats, horses/cows, small dogs
• B. Giant dogs, horses/cows, adult cats, small dogs
• C. Adult cats, giant dogs, small dogs, horses/cows
• D. Horses/cows, small dogs, adult cats, giant dogs

Answer: (A)

Maintenance rate reflects how much energy an animal needs at rest to keep basic body functions going. It isn’t a simple line with size—smaller animals generally burn more energy per unit body mass, but the total daily maintenance also depends on how efficiently different species use energy. In this group, the largest dogs (giant breeds) have the lowest daily maintenance when compared across these species, because their energy turnover per unit body weight is comparatively lower than that of smaller companions. Next come the adult cats, whose resting metabolism is high for their size, so their maintenance requirement exceeds that of giant dogs. Larger herbivores like horses and cows require substantial energy to support their big bodies, pushing their maintenance above cats. Finally, small dogs, despite their small size, have a relatively high metabolic rate per unit body weight and enough total mass to raise their overall maintenance needs, making them the highest among the four. Therefore, the ranking from lowest to highest maintenance rate is giant dogs, adult cats, horses/cows, and small dogs.