单选题 The microphone makes the voice sound louder because it concentrates sound waves in one direction and keeps them from ______ in all directions.

【正确答案】 D

【答案解析】[解析] 动词词义辨析。keep sb. from doing sth. 阻止某人做某事。根据句意，这里应该是“聚光，防止光线向四面八方发散”的意思。disperse一般指云的散开；spread一般指消息的散布；distract可以指光的“分散”。故答案为D。