问题详情

Mouthwashes are not effective cure for bad breath mainly because

A．they can"t cover the thick layers of mucus.

B．they can"t get to all the offending bacteria.

C．they can"t mask the bad odor long enough.

D．their strong smell mixes with bad breath and makes it worse.

请帮忙给出正确答案和分析，谢谢！