Answer:
practical intelligence
Explanation:
According to my research on studies conducted by various neurologists, I can say that based on the information provided within the question this is an example of practical intelligence. This type of intelligence is defined as an individuals ability to find the best fit between themselves and the environment, which in other words is the ability to learn and develop your motor skills (physical movements) in order to adapt to a situation. Which is what Johnny is doing by learning to climb the stairs just by observing his brother.
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