(Adapted from: . Access: December 1, 2011.)

Consider the following sentence and the three alternatives to complete it.

Calvin said, “I will never teach maths”. In the indirect speech this becomes

1 - Calvin said that he would never teach maths.

2 - Calvin said that he is never going to teach maths.

3 - Calvin said that he was never going to teach maths.

Which of the alternatives above can be considered grammatically correct?