Greg is 10 months old, and he refuses to crawl across the visual cliff even though his mother is encouraging him to do so. when he was 6 months old, he squirmed across it without hesitation. what has changed for greg?

The perception of depth of Greg has developed

Explanation:

The perception of depth of babies, which started to develop in the 6th month, completes its development to a great extent from the tenth month. Depth perception protects Greg from accidents such as crashing around objects or falling down stairs. Therefore, he refuses to crawl across the visual cliff.

sounds good to me mate!

rain should be the answer.