Answer is A.
Archaea requires neither sunlight for photosynthesis as do plants, nor oxygen. Archaea absorbs CO2, N2, or H2S and gives off methane gas as a waste product the same way humans breathe in oxygen and breathe out carbon dioxide. An example is chemosynthetic bacteria by sea drifts. They use chemical energy to produce vital processes to live.
Capsid is the component of a virus that is lacking in its cell
A capsid is the protein shell that surrounds a virus. Capsids functions by protecting the nucleic acids of a virus while interacting with the host environment. Capsids are made up of many oligomeric structural subunits that contains the protein; protomers. Capsids are generally grouped based on their structure. The common ones are helical and icosahedral.
Rigid skeletons are formed from materials including chitin (in arthropods), calcium compounds such as calcium carbonate (in stony corals and mollusks) and silicate (for diatoms and radiolarians).
In humans, the maintenance of a stable internal temperature is a direct result of Homeostasis. Homeostasis is the ability of the body to maintain an equilibrium condition within it's internal environment even when dealing external changes. Homeostasis happens in human when there is an effort exerts by the body to regulate it's internal temperature around 98.6 degrees Fahrenheit. For example, during summer days we produce sweat for our body to cool off, and during winter we shiver for our body to produce heat.
