How does Tiburcio know Don Andres Pico, securing Pico as a trustworthy ally?

A. They were in the same gang when they first started their careers as bandits.
B. They served together in the Mexican-American War.
C. They are brothers-in-law (Pico married Tiburcio's sister).
D. They grew up in the same church, and Pico used to be his pastor.