Astoreowner places a “no smoking” sign in front of their store. this would be classified as a type of factor.   

A No Smoking sign, it's a protective factor for health, or a preventive health factor, since it prevents possible diseases that active smokers, and liabilities have, while encouraging people to throw their cigarettes, or not to smoke to be able to enter buy from stores. This is part of anti-smoking laws and many governments demand it, so that in the shops, people do not smoke and thus protect the health of young people and children, and non-smokers in general. While traders have to accept these bans by law, it is to be noted that it will help reduce the risk of cancer, and will save a lot of money on treatments for chronic smokers.

The answer is d. worthless