(S)-Amphetamine is a commercially available drug used as a CNS stimulant. Considering the fact that (S)-amphetamine rotates the plane-polarized light in the clockwise direction, answer the following questions:
(a) Should (S)-amphetamine be referred to as (d) or (l)?
(b) Should it be referred to as (+) or (−)?
(c) What would be the direction of rotation (d or l; + or −) for (R)-amphetamine?

• A. (a) (S)-Amphetamine should be referred to as (l).
  (b) (S)-Amphetamine should be referred to as (−).
  (c) (R)-Amphetamine should be referred to as (l) and (+).
• B. (a) (S)-Amphetamine should be referred to as (d).
  (b) (S)-Amphetamine should be referred to as (+).
  (c) (R)-Amphetamine should be referred to as (l) and (−).
• C. (a) (S)-Amphetamine should be referred to as (d).
  (b) (S)-Amphetamine should be referred to as (+).
  (c) (R)-Amphetamine should also be referred to as (d) and (+).
• D. (a) (S)-Amphetamine should be referred to as (l).
  (b) (S)-Amphetamine should be referred to as (−).
  (c) (R)-Amphetamine should be referred to as (l) and (−).

Answer: (B)