Final answer:
Definite chemical composition that can vary within specified limits is NOT included in the definition of a mineral.
Therefore, the answer to the question is A.
Step-by-step explanation:
A mineral is defined as a naturally occurring, inorganic solid with a definite chemical composition and a characteristic crystalline structure.
By naturally occurring, it means that anything humans have created, like synthetic bismuth, does not count as a mineral.
A definite chemical composition refers to the chemical formula of a mineral, and this composition can vary within specified limits. Therefore, the answer to the question is A. Definite chemical composition that can vary within specified limits is NOT included in the definition of a mineral.
Therefore, the answer to the question is A.