Pollution cleanup efforts can be ineffective because

Pollution cleanup efforts can be ineffective because
 
  a. They often transfer pollutants from one part of the environment to another.
  b. Once pollutants are dispersed, it costs too much to reduce them to acceptable levels.
  c. They can be overwhelmed by growth in population and consumption.
  d. They often transfer pollutants from part of the environment to another, once they are dispersed it costs too much to reduce them to acceptable levels, and they can be overwhelmed by growth in population and consumption.
  e. There are not enough people with the necessary technical training to deal with the problems.