为自己加油

Choose the closest paraphrased version after the following sentence or the italicized part. 

Sometimes I think how grateful I would be today if I had learned more back then about what really matters.（）

A.
Sometimes I feel happy that I was taught what is important at school.
B.
Sometimes I feel sorry that I didn't learn what is important at school.
C.
At times I feel resentful that I was not taught anything useful at school.
D.
At times I feel I should be thankful for those things I learned at school.