Answer:
Secondary circular reaction
Explanation: this occurs between babies of about 4-8months. Here, children acquiring pleasure from toys, object in their environment by playing with them. In this stage, children uses items or object to learn about the world. They use object by throwing them, playing with them and when they derive pleasure or happiness from playing with it, they become happy and do it continuously. In this substage, children do things and mostly expect reaction from the environment. Example they throw toys and the sound of it hitting the ground will make them happy or sad. And they will continuous do that action if they are happy with the sound it makes or find pleasure in them.