题目

Many people catch a cold in the springtime or fall. It makes us wonder. If scientists can send a man to the moon, why can’t they find a way to deal with the common cold? The answer is easy. There are actually hundreds of kinds of cold viruses out there. You never know which one you will get, so there isn’t a cure for each one. When a virus attacks your body, your body works hard to get rid of it. Blood rushes to your nose and brings congestion（拥塞）in it. That is to say, you cannot breathe well. As a result, you feel terrible. However, your body is actually “eating” the virus. Yo若，则3x+2y的最小值为 [     ]A．4B．8C．D．