Which of the following words are correct in stress？（）

Which of the following words are correct in stress？（）
A.economy /?'k?n?m?/
B.economist /?'k?n?m?st/
C.economic /?'k?n?m?k/
D.economical /?'k?n?m?kl/
正确答案：economy /?'k?n?m?/；economist /?'k?n?m?st/