Final answer:
The term for a group of minerals with different compositions but arranged in the same type of crystal structure is 'Polymorphs'. option a.
Step-by-step explanation:
The correct answer to the question is A. Polymorphs. A polymorph is a substance that can have the same chemical composition but exists in different forms due to variations in its internal atomic arrangement and crystal structure. Polymorphism is a characteristic that can appear in various crystalline materials including minerals, polymers, and metals. Notably, this phenomenon explains how substances with identical chemical formulas can have different physical properties. It is also worth noting that polymorphs are distinct from allotropes, which refer to different forms of the same element in the same physical state but with different chemical structures. However, both concepts highlight nature's ability to arrange atoms in diverse ways, giving rise to substances with a variety of structures and properties.
Polymorphs share the same chemical formula but differ in internal atomic arrangements and physical properties. This phenomenon is not restricted to minerals but can occur in various crystalline materials.