Context: The following passage describes the effects of a gene mutation, which is a permanent change in a gene. Read the passage and then follow the instructions below.

The hairs in a jaguar's coat are colored by molecules called pigments. The pigments are made in cells at the base of each hair. When these cells make light pigments, the hair is light-colored. When these cells make dark pigments, the hair is black.
A protein called MCR1 controls how the jaguar's cells color each hair with light and dark pigments. The function of the MCR1 protein results in jaguars with spotted coats, made up of both light-colored and black hairs. The MCR1 protein is encoded by the MCR1 gene.
A certain jaguar had a solid black coat because of a mutation in its MCR1 gene. Compared to the MCR1 gene without a mutation, the mutated MCR1 gene encoded a form of the MCR1 protein with a different structure.
This different form of the MCR1 protein allowed only dark pigments to color the hairs.
Figure: a jaguar with a solid black coat (left) and a jaguar with a spotted coat.
Complete the sentence.
The mutation in the () affected the structure and function of the ().
A. MCR1 protein . . . MCR1 gene
B. MCR1 gene . . . MCR1 protein
Choose the right answer from the options and respond with its letter.

B