As employees use instant messaging to conduct more business，they should send messages that are informal，conversational，and（）

As employees use instant messaging to conduct more business，they should send messages that are informal，conversational，and（）
A.professional.
B.streamlined （e.g.，using abbreviations such as ur for you are）.
C.filled with slang and jargon.
D.casual，including low-level language.
正确答案：professional.