The onset of action of a drug is primarily determined by the rate of

Which of the following statements are true regarding onset, degree and duration of action of local anesthetics?
a. The greater the drug concentration, the faster the onset and the greater the degree of effect
b. Local anesthetics block only myelinated nerve fibers at the nodes of Ranvier
c. The larger the diameter of the nerve fiber, the faster the onset of effect
d. The faster the penetrance of the drug, the faster the onset of effect