The absolute value sign makes it so that k+7 could be either -3 or +3 and the result would still be 3. This means there are two possible answers for k. The one that makes k+7=-3 and the one that makes k+7=+3. Just solve these two equations: k+7=-3 k=-3-7 k=-10
k+7=3 k=3-7 k=-4
So the possible answers are -4 and -10. B is the correct choice.