Krishna answers immediately and directly. Every living being's faith comes in three varieties — sattvic, rajasic, and tamasic. And this faith is not random. It arises from the person's own inner nature. Whichever guna dominates within, that person's faith will reflect it.
Consider a garden where different plants produce different flowers. In the same way, people of different inner constitutions naturally gravitate toward different objects of faith. One person is drawn to knowledge and peace, another to power and display, and yet another to superstition and darkness.
Krishna tells Arjuna: listen, I will explain all three in detail. This single shloka sets up the framework for the entire chapter.