Answer "B" is the correct option.
By the mid-1700s, the Spanish conquistadors brought their horses with them when they crossed the Atlantic to the New World. some horses escaped while others swam towards the shore after ships sank. The Native Americans caught the horses, trained them and learnt how to ride these animals. It was an unintentional consequence, since the plains Indians became expert horsemen who relied on their herds for buffalo hunting and trade.