Which of the following is NOT a primary reinforcer?

1. A primary reinforcer has innate reinforcing qualities and is not learned. 2. Food, water, sleep, shelter, sex and touch all satisfy needs directly, so all are primary reinforcers. 3. Money has no inherent value and reinforces only because it can be exchanged for other things. 4. Money is therefore a secondary reinforcer; the chapter makes the point that stacks of money on a remote island would reinforce nothing. _Source: OpenStax Psychology (1st ed., CC BY 4.0), Ch 6 "Learning", §6.3 Operant Conditioning_