Four out of seven Chestnut High School Chess Academy students (A, B, C, D, E, F and G) are to be selected in a school chess team in such a way that if A is selected, then B cannot be in that team and if B is selected, then E cannot be in that team. If one of D and F is selected, then the other must be chosen. Which of the following statements must be true?
If B is selected, then D must be chosen.