Consider the following : (1). Bats (2). Bears (3). Rodents The phenomenon of hibernation can be observed in which of the above kinds of animals?

Hibernation is a state of deep torpor in which metabolic rate, body temperature and heart rate fall sharply so that an animal can survive a cold season with scarce food. All three groups show it, so the answer is C.

• Bats: Many temperate-zone bats enter prolonged torpor in caves and hollow trees through winter, when their insect food is unavailable.
• Bears: Black and brown bears den up in winter and lower their metabolism. Their body temperature falls less than in small mammals, which is why some biologists call it walking hibernation.
• Rodents: Ground squirrels, marmots and dormice hibernate, with body temperature dropping close to ambient levels.

Options A and B leave out one or more of these groups, which is the error most people make when they think of hibernation only in small or large mammals. Option D is wrong because each group has documented hibernating species.

The core concept is adaptation to seasonal stress through physiological strategies. This links to the Environment and Ecology section on adaptations and to Mains questions on biodiversity in cold regions.

Trap: Assuming bats or bears cannot hibernate because they fly or are large. The question tests the taxonomic range of hibernation, not just the textbook examples.