All of the things listed in the choices are positive effects of having communication. It teaches people how to present themselves appropriately to the audience, yes, because you communicate with different types of people every day. And each day, you learn new approach.
It'll help you become a better leader becuase through communication you will understand what your members need.
Communication is also one way of having an effecient group by brainstorming. It also establishes effective listening skills because you can't just talk everytime you communicate, you also have to listen to have a good flow of communication. So the answer is E.
