Which of the following is a false statement about dietary supplements?
a. They do not have to be proven safe before they are offered for sale on store shelves
b. There is no system in place to monitor the purity of dietarty supplements
c. There is no requirement to supply evidence to any regulatory agency that the claims made on the product label are truthful
d. Contamination of dietary supplements with substances that are banned by various sport governing bodies is fairly common
e. All the above are true