The correct answer is to support the army to contribute to their own upkeep.
Answer:
https://www.sparknotes.com/lit/odyssey/section8/
Explanation: Odyssey Books 15 - 16, i think thats where you'll find it. (Copy and Paste)
There were many advances both scientifical and technological during Islam's Golden Age. One example here was algebra which stems out of the thughts and intellectual discussions of Islamic thinkers during this time. This advance in particular had an immense influence on the future development of mathematics and other scientific disciplines. Mosques here helped spread the knowledge that was being developed and shared at the time.