As of 2009, about 40 countries were involved in projects to test alternative malaria treatments. Instead of DDT, countries can use pyrenthroid insecticides, which are generally harmless to humans in low doeses, or they can drain standing water where mosquitoes breed. Alternative approaches have been successful in Mexico and Central America. Other areas, however, have seen disturbing increases in malaria when they have stopped using DDT. In South Africa, one mosquito strain was resistant to pyrethroids. When DDT was discontinued, the number of malaria cases soared from 4,117 in 1995 to 64,622 in 2000. Nothing but DDT has proved to be consistently effective in stemming the increased occurence of this disease. why does Velasquez include the detail about 40 countries testing alternatives to DDT in preventing malaria?

a. To show the number of countries banning DDT as a malaria prevention in 2009

b. To show the number of countries that wanted an effective replacement for DDT in 2009

c. To show the number of countries of countries concerned about increased malaria cases in 2009

d. To show the number of countries that had eradicated (means reduction) malaria in 2009