Which of the following be going to + infinitive construction is used to express intention?

Which of the following be going to + infinitive construction is used to express intention?
A.He is going to be a teacher when he grows up.
B.I feel dizzy. I think I am going to faint.
C.George is putting on weight. He is going to be quiet fat.
D.Look at these black clouds — there is going to be a storm.
正确答案：He is going to be a teacher when he grows up.