Hibernation is an adaptation which has evolved in certain group of animals to conserve energy by slowing down metabolism and keeping their body temperature low in winters.

• Bats and bears are well known for hibernating. Some of the hibernating animals includes fish, frogs and turtles, snakes, bees, hedgehogs which have no way to keep warm during winter.
• Hibernation helps animal to survive when there is inadequate food supply. Before entering into hibernating state an animal stores enough fat to consume it during hibernation.

So, the correct option is 'Hibernation '.

• Ecology is the study of interaction between living organism and their environment. The basic unit of study in ecology is organism .
• An organism is a single living entity that can carry out all the functions of life, such as obtaining energy and nutrients, responding to the environment, and reproducing.

• A  xerophyte  is a species of  plant  that has  adaptations  to survive in an environment with little liquid water, such as a  desert  or an ice- or snow-covered region in the  Alps  or the  Arctic.
• Succulent (a xerophyte) plants  store water in their stems or leaves.

• This is a large regional unit characterised by a major vegetation type and associated fauna found in a specific climate zone.
• The biome includes all associated developing and modified communities occurring within the same climatic region, e.g., forest biomes, grassland and savanna biomes, desert biome, etc.
• On a global scale, all the earth ’s terrestrial biomes and aquatic systems constitute the biosphere.

The Father of Ecology in India is Ramdeo Misra.

• Raja Ram Mohan Roy was a freedom fighter.
• Verghese Kurien is the Father of the White Revolution of India while MS Swaminathan is the Father of Green Revolution of India.

The place where a particular organism lives called a habitat.

• It is a place where an organism can find shelter, food, mates for reproduction and, protection from predators.
• It depends on both biological and physical factors present within it.

Homeotherms : Animals who maintain a constant internal body temperature across a wide range of environmental conditions. Most mammals and birds are homeotherms.

The population has the same number of individuals in the pre-reproductive post-reproductive age is called a steady population.

• It is the population in which the birth rate is approximately equal to the death rate.
  

• Ectotherms   are  so-called cold-blooded animal that is  any  animal  whose regulation of body temperature depends on external sources, such as  sunlight  or a heated rock surface.
• The ectotherms include the fishes, amphibians, reptiles, and invertebrates.
• The body temperatures of aquatic ectotherms are usually very close to those of the water.
• Ectotherms do not require as much food as warm-blooded animals (endotherms) of the same size, but most cannot deal as well with cold surroundings.

• Biological organisms starts with sub-microscopic molecular level l ike viruses, bacteria etc.
• These organisms are unable to be seen by naked eyes without the help of microscope or even electron microscope.