Answer:
A. They were fought by the soldiers of the Qing Dynasty.
People brought Ladybugs over to America to get rid of aphids, but the Ladybugs became a pest too.
Answer:
Once they embarked, settlers faced numerous challenges: oxen dying of thirst, overloaded wagons, and dysentery, among others. Trails were poorly marked and hard to follow, and travelers often lost their way. Guidebooks attempted to advise travelers, but they were often unreliable.
This is called the frustration of purpose. It's a doctrine about how cases would be solved if unforeseen circumstances were to occur. A modern example would be if you took a mortgage but an earthquake completely destroyed your house. Due to the frustration of purpose, you could have your mortgage canceled because you don't have a house that the mortgage was for, so you wouldn't have to pay for it any more.
