听力原文：Man: Because you need water for various reasons, you often end up making your overnight camp by a river. Providing you take care to keep insects away, this can be as healthy a place as any. Much as you might feel you need a good wash, one trap not to fall into, though, is the use of soap or shampoo. These may make you feel good, but actually give off unnatural smells in the jungle which act as a magnet to insects, thus increasing the chances of your getting bitten. Better to actually go in for a dip, being careful to dry off and re-apply your anti-insect cream immediately afterwards.
You hear a man talking to a group of people who are going on an expedition into the rainforest. What does he advise them against？ ......

A. sleeping in places where insects are found.
B. using substances which attract insects.
C. bathing in areas where insects are common.