Answer:
D! The titanic.
Titanic was one of the few ships to be thought as "unsinkable". Yet on it's first voyage, it sunk!
The most important impact of the improvements in saddles in assisting the spread of Islam to Sub-Saharan africa is they they contributed the increase in Trans-Saharan Trade. They help to increase the trade in the region so that Its not hard to trade some of the product.
the spread of Christianity
