Why did Islamic rulers want to increase literacy among their subjects?

Question

a. He wanted his priests to be able to write down their teachings
b. He wanted his subjects to be able to read the Quran
c. He wanted his scholars to be able correspond with Europeans
d. He wanted his merchants to be able to record their business dealings

Answer 1

The most fitting answer is:

b. He wanted his subjects to be able to read the Quran.

Increasing literacy among subjects would facilitate a greater understanding of the Quran and Islamic teachings, which is a central goal in many Islamic societies historically.