CH3CH2CH2CH2+(I)，CH3CH+CH2CH3(II)，(CH3)3C+(III)三种碳正离子稳定性顺序如何?

CH3CH2CH2CH2+(I)，CH3CH+CH2CH3(II)，(CH3)3C+(III)三种碳正离子稳定性顺序如何?
A.II>I>III
B.I>II>III
C.III>II>I
D.II>III>I
正确答案：III>II>I