Answer:
The answer is B. weakened military
Step-by-step explanation:
This is directly from PF reading material. Look at the first line.
"The Safavids collapsed in 1722 mainly because of the weakening of their army. In earlier times, the Safavids were able to beat back outside threats from both the Ottomans and the Mughals. However, by 1722, they were incapable of even defending themselves against poorly armed Afghan tribal forces. During the previous decades, there was little investment in modernizing the infantry and cavalry. The Afghan attack began as a revolt against a Safavid governor but became a war against the Safavid leader, Sultan Husain. Ultimately, the Safavid ruler lost and abdicated his throne. Although there were attempts to revive the Safavid rule, they were mostly unsuccessful. In the eighteenth century, Iran broke down into tribal law, with five different dynasties ruling different regions."