A vaccine can help keep people healthy and protect them from a certain virus. For example people in the United States get the flu shot when they get this shot the vaccine wont magically get rid of the virus but rather help them fight it off and protect them in the future if they keep up to date getting the vaccine
Example of selective breeding: Cows that produce lots of milk. Selective breeding to create more useful varieties of animals and plants is a form of biotechnology that human beings have used for thousands of years. Biotechnology includes any use of science or technology to alter the characteristics of a particular breed or animal.
Answers:
Yes , restrictions should be given on who can buy explosives. In short only authorised officers should always investigator users of explosives, they should investigate safety and security matter that has to do with explosives. They should make a strict regulations and penalty for defaulters. I think advice should be given users and buyers that has access to, explosives to protect public safety, property and the environment.