The correct answer is A. Compare and contrast
Explanation:
In writing, the term "organizational structure" refers to the way the information in a text or section is organized, which is commonly linked to the content of the text and the purpose a text has. In the case of compare and contrast organizational structure, this is used to analyze the differences and similarities between to subjects or elements that belong to the same category and usually by stating first the common point and then the points that make the elements different or vice-versa.
This is the case of the passage presented in which the author states first the common points between two cats "They both have that luxurious long hair and those piercing green eyes" and the points that made the cats different "I like that one is completely white, while the other is pure black", therefore the organizational structure used is compare and contrast structure, because the author analyzes the differences and similarities of two subjects, which in this case are two cats.