Which type of study is the most likely to meet the criteria for causal inference?

Children are able to develop their own memory aids and organize information on their own at ______ years old

2–5 5–7 7–8 9–11

Among adults, a fear of flying is thought to reflect a fear of falling, or loss of support. In infancy, the ________ reflex protects the infant from falling

a) rooting b) grasping c) sucking d) Moro startle