Which thesis statement below is less effective ？

Which thesis statement below is less effective ？
A.Preparing for a PowerPoint presentation can really be quite easy.
B.In this essay I want to discuss what the government should do to help homeless children.
C.You can acquire a competitive spirit by practicing five personality traits.
D.New employees must go through four training sessions before they start to work.
正确答案：In this essay I want to discuss what the government should do to help homeless children.