The most common ways to treat cancer include

radiation therapy, chemotherapy, immunotherapy, targeted therapy, or hormone therapy.

the correct answer is 4 (giveaways to the public)

something that is given away or gave out for free. an occasion at which things are given away to free. something that is evident or obvious; something that uncovers a mystery.

it could be be in a form of a lucky draw as well. these the company events gather more audience for their pr and it also increases their ratings as well. this is a way to attract more customers towards themselves.

                                                        water

a colorless, transparent, odorless, tasteless liquid that forms the seas, lakes, rivers, and rain and is the basis of the fluids of living organisms.

                                                        halon  

any of a number of unreactive gaseous compounds of carbon with bromine and other halogens, used in fire extinguishers, but now known to damage the ozone layer.

                                                  dry chemical

extinguishing agent used on class a, class b, and class c fires.

                                                  carbon dioxide

a colorless, odorless gas produced by burning carbon and organic compounds and by respiration. it is naturally present in air (about 0.03 percent) and is absorbed by plants in photosynthesis.