Final answer:
The subject of the quote is belief, as Mariam teaches Aziza verses from the Quran, demonstrating her unwavering belief in its teachings.
Step-by-step explanation:
The subject of the given quote is belief. Mariam is teaching Aziza verses from the Quran, which she considers to be her true possession. This demonstrates her unwavering belief in the power and importance of the Quran and its teachings. The Quran is the holy scripture of Islam and Muslims believe it was given to humanity by God through Muhammad, making it a central component of their belief system.