Final answer:
The term 'sibling' is not a recognized type of magma in geological classification; instead, parental, primary, and evolved magmas are the fundamental types.
Step-by-step explanation:
The option that is not a fundamental type of magma is a. Sibling. When classifying magma, the terms used are parental magma, which is the original magma source, primary magma, which is the magma that has not undergone any differentiation, and evolved magma, which has been altered by processes like fractional crystallization or contamination. Sibling magma is not a recognized term in this context.