The city is thinking about starting a program to add a new chemical to the public pool. Before they do, they want to find out if there are any health risks associated with this type of chemical. Which group would be the best to advise them on this topic?

a group of concerned citizens who oppose the program
the company that manufactures the chemical
the local pest pool companies who would be hired to take care of the pool
the government agency that regulates these types of chemicals