I believe the answer is: <span>infants pay attention to facial expressions and smile more at smiling faces.
</span>When entering 3 months old period, Most infants would develop the ability to recognize emotion from other people around them.
This would make them pay attention to facial expressions and would started to learn which emotions are positive and which emotions are negative.
<span>The federal system is characterized with a divided authority, usually by a written constitution, between a central government and constituent (state) governments.</span><span>
Federal legislation that requires states and municipalities to comply with certain rules is known as a federal mandate.
</span><span> It is a requirement or an order from the central government that all state and local government must comply with.</span>
South Africa; migrant workers; they spend most of the year working in mines and factories, visiting their families only a few times each year for brief periods
The abbasid caliphate founded Bagdhad.
What do you mean by "this"? Do you mean heliocentric model, that is, with Sun at the center and all the planets (including the Earth) surrounding it and circling around it?
Then the correct answer is:
Nicolas Copernicus, a Polish Astronomer