D.they dis not want the goverment to regulate them.
This would be true if thats what your looking for
Diltiazem (cardizem) and amlodipine (norvasc) would be most likely to have opposite effects on heart rate. Diltiazem (cardizem) has effects on blood pressure ( used by patients whit high blood pressure), just like amlodipine (norvasc), but beside that, diltiazem (cardizem) works to regulates heart rate.