Babies, especially those who are at least 4-6 months old, have the tendency to explore objects by touching and holding them, and putting them in their mouth. By this time, it is very important to keep small objects out of their reach so that accidents can be prevented.
Answer:
Biological predisposition of learning
Explanation:
There are some inbuilt likeliness towards doing a work even when subjected to external stimuli. This tendency is known as Biological predisposition of learning. A person (here the baby) will wave the banner only when he/she is exposed to desired stimuli. Since the parents are not aware of those desired stimuli conditions, they are unable to make the baby wave the banner even though he/she picks up the banner.
Thus, "Biological predisposition of learning" is keeping the baby from learning to wave the banner
