question: Q:Which one sentence explains most accurately why spin trapping is often used to detect free radical intermediates?? 
  A:spin trapping provides more structural information than direct detection by EPR;B:spin trapping makes it easy to quantify free radical intermediates;C:steady state concentration of free radical intermediates is often too low to enable direct detection by EPR;D:detection of spin adducts requires lower power than direct detection of radical intermediates