Graphene is:

Allotrope of Carbon

The correct answer is option 3. Allotrope of Carbon.

Graphene is an allotrope of carbon.

Allotrope: Allotropy refers to the existence of an element in two or more different forms, or allotropes, in the same physical state. In the case of carbon, it can exist in various forms, including diamond, graphite, fullerenes, and graphene. Each of these forms has distinct structural arrangements of carbon atoms.

Carbon is a chemical element with the symbol "C" and atomic number 6. It is known for its versatility and ability to form strong bonds with other carbon atoms and various elements.

Graphene:  Graphene is a single layer of carbon atoms arranged in a two-dimensional honeycomb lattice. It is incredibly thin, strong, lightweight, and has remarkable electrical and thermal conductivity properties. Graphene is considered one of the most promising materials for various applications, including electronics, energy storage, biomedical devices, and more.

In summary, graphene is a specific form of carbon, consisting of a single layer of carbon atoms arranged in a unique lattice structure, making it an allotrope of carbon.