You Plan a Study Where You Want to Identify Who

You plan a study where you want to identify who is an attachment figure for a given child. You pit one parent against a sibling and a grandparent. How could you identify which person is the strongest attachment figure based on an infant's behavior?

A) Observe towards which person the infant is directing cries or gestures indicating to be picked up when placed on the ground.
B) Observing the play behavior between each person and the infant when engaging in one-on-one play sessions.
C) Presenting the child with the scent of one of these familiar people and the scent of a stranger. If the child preferentially orients towards the scent of one of these familiar people more than 50% of the time, then that person is an attachment figure.
D) All of the above.