Which of the following is a potential obstacle to the commercial development of brownfields?
a. the presence of pollutants
b. environmental cleanup laws
c. the costs of environmental cleanup
d. all of the above

 d) all of the above

"The presence of poisons", "ecological cleanup laws" and "the expenses of natural cleanup" are all a potential impediment to the business advancement of brownfields. The right alternative among every one of the choices that are given in the inquiry is the fourth choice i.e all of the above

c. is the correct answer