A.1237 has 3 correct, so there are at least 2 correct in 127. 4721 has 2 correct, therefore they all have to be in 721=>4 is false.
B. In 2169, if 21 were both true, then 69 would both be false, but then in 3694 we would be left with only one possible true (3), so 21 both being true has to be false. From this it follows that in 721 there are exactly two true numbers=>3 has to be true.
C. Since there is only one true in 21, and 4 is false, in 4721 7 has to be true. For the same reason, in 2169 there has to be one true in 69.
D. (here starts a massive step to show that 2 is false and consequently 1 is true)
F. There is one true in 69, and in 8951 there are two true, one of which is established from step D to be 1. Since we already know that three numbers (1,7,3) are true, and there is 1 true in 895 and one true in 69=>9 is true (otherwise there'd be more than 4 true numbers).
G. (finding the order -3719- was easy, I just haven't typed out how it was
)