Please help me it will be very much appreciate:-)

What are economic systems and how do they differ?

Why did the fighting go on after the armistice was signed

Which of the following world and national events led to a new view of people with disabilities in the us:     a.  world war i and ii veterans with disabilities returned home after the wars.b.  john f. kennedy was elected president and had a sister with a disability.c.  the civil rights and feminist movements.d.  all of the above.