There Are Four Options for Shaping Behavior in Operant Conditioning

There are four options for shaping behavior in operant conditioning. Which of the following is the best definition for positive reinforcement or reward?

A) Rewards desired behaviors by adding something desirable (e.g., a treat)
B) Rewards desired behaviors by removing something undesirable (e.g., relaxing curfew)
C) Reduces undesirable behavior by adding something undesirable (e.g., assigning extra chores)
D) Reduces undesirable behavior by removing something desirable (e.g., grounding)