Writing in a diary, watching television, talking with friends, speaking on the telephone, and __1__ a menu -- what do they have in common? They are all __2__of communication. It has been__3__ that people spend more time communicating than they spend in any other complex activity in life.__4__ communication is a word that most people have difficulty __5__and talking about. The word communication may be used to identify activities that do not__6__people. For example, the word may sometimes be used to describe the __7__that animals relate to each other. __8__, it is said that electronic devices "communicate" with each other. However, communication most often refers to activities among people. Thus, communication may be defined as the__9__by which people exchange feelings and ideas with one another. __10__this definition is clear and simple, much more needs to be said.
（9）下列正确的是（ ）

A.measures

B.means

C.modes

D.manners