Tại sao nói thuế suất là yếu tố trọng tâm của các yếu tố cơ bản của luật thuế?

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.