Read the assertion and reason carefully and answer the question on the basis of following options. You have to select the one that describes the two statements.

Chemical element carbon, with atomic number 6, is denoted by the letter C. It has three naturally occurring isotopes and is found in the earth's crust as the fifteenth most prevalent element. It is a member of the 14th group of the periodic table.

Catenation is the self-linking of an element's atoms to create chains and rings. This definition may also be expanded to include the formation of layers, such as two-dimensional catenation, and space lattices, such as three-dimensional catenation. Carbon often undergoes catenation because it creates covalent connections with other carbon atoms to build larger chains and structures. The investigation of catenated carbon structures in organic chemistry has made carbon best recognised for its catenation capabilities.

Therefore, based on the explanation above, we may infer that option A is the right response, meaning that catenation is the mechanism that explains why carbon can build long carbon chains.

Thus, the correct option is (A).