Their metal construction made them very durable
Indulgences. Indulgences were payments to the church to reduce the amount of punishment on judgement day. These payments were considered to be the one of the main corruptions of the Catholic church leading Martin Luther to challenge them. I hope this helped.
Answer:
The actual answer that isn't listed in there is 9.6M people. So I would go with 1.5M
Neutrality. (Assuming that's one of your options)