Food because income is money you take in.
a. more efficient because polluters that can only reduce pollution at high cost do not and instead buy allowances.
Answer: a. marketing
Explanation:
Using email for marketing purposes has become a very effective method of advertising since the advent of the internet and subsequently email services. It is quite low cost and yet has a wide coverage.
It also enables immediate communication that can be quite interactive thereby ensuring that customers can be personally catered for. It also allows for creativity in marketing as a multitude of methods can be used ranging from newsletters to posters.