Final answer:
The symbol 'O' referred to in the options stands for 'Omega,' the last letter of the Greek alphabet, frequently used in mathematics and related disciplines.
Step-by-step explanation:
The official name for the symbol 'O' in the context of the options provided is Omega, which is the answer choice (a). Omega is the 24th and last letter of the Greek alphabet, and in mathematics and other fields, it is used to represent various concepts. For instance, in mathematics, it can denote the omega constant, an important value in Lambert W functions, or in number theory, it can symbolize the number of distinct prime factors of a given natural number. Omega is also often used to represent the idea of infinity or the last thing in a series, which is a common poetic reference to something's ultimate nature or finality.