Final answer:
The pair of minerals that are not polymorphs is b. chlorite and biotite. Polymorphs share the same chemical composition but have different internal structures, and chlorite and biotite, being mica-group minerals with different chemical compositions, do not meet this criteria.
Step-by-step explanation:
The question asks which pair of minerals are not polymorphs. Polymorphs are two or more minerals that have the same chemical composition but differ in their internal atomic arrangement and crystal structure. The given options include pairs of minerals, and we must identify the pair that does not represent polymorphs. From the provided information, we know that kyanite, sillimanite, and andalusite are polymorphs, as they have the same chemical composition but different internal structures. Therefore, we can eliminate option a. For the remaining options, chlorite and biotite are both mica-group minerals, but they have different chemical compositions, so they are not polymorphs. Hence, the correct answer is b. chlorite and biotite, as they do not share both composition and structure.