C is the answer hope i helped
Quit drinking and smoking but B is the most important one tbh
Because it has the same soothing properties that can increase the saliva in your mouth which lubricates the throat so it feels better
Probably gloves and a mask, because the most common transports of the flu, is people geting germs on their hands, which are carried to their mouth. A mask would prevent bodily fluids on the hands from getting in the mouth, and gloves will prevent bodily fluids from adhering to the hands.
There's not really a specific way, but be persistent. If you don't agree, say no. Don't let them change your mind