The descriptors "positive" and "negative,"when used in reference to reinforcers, are synonyms for.
a. "New" and "familiar"
b. "Add" and "remove"
c. "Increase" and "decrease"
d. "Voluntary" André "involuntary"
e. "Conditioned" and "unconditioned"

b) "Add" and "remove"

Explanation:

In terms of operant conditioning, positive and negative reinforcer is used for describing reinforcement for behavioral response possibility. Positive reinforcement is defined as addition of stimulus for response improvement .Negative reinforcement is based on elimination of stimulus that cause increment in response likelihood.

Other options are incorrect because increment and decreasing, new and familiar, voluntary and involuntary  and conditioned and unconditioned  are not the description to defined reinforcer in operant conditioning. Thus, the correct option is option(b).