You can accomplish more with others than alone because it’s not just 1 mind that’s thinking and processing, it’s multiple. For example, if your doing a math question by yourself you might not know the answer. But, if you have a partner then they might know the answer and can help you answer the question.
During this stage, you look for and correct any mistakes you may have made, and/or change a few things to make the writing flow better. Hope this helps you!
A. an adjective (because it's describing the subject)
I think it would be the first one, although I am not positive.