The important detail here is not the posture or the expression, but the hair color.

Take a closer look at the girl's hair and compare it to the two women. Woman B has the same hair color as the child, which is a strong visual clue that they are related. It's a small detail, but in image puzzles like this, these little things reveal a lot. Of course, not every child looks exactly like their parents, but in this puzzle, the matching hair color is the biggest hint.