Brian volunteers at a soup kitchen on Wednesdays when French Onion soup is being served. When he walks into the kitchen, his eyes begin to water because of all the onions being cut. One week, Brian volunteers at the same soup kitchen on a Monday when they serve ham sandwiches, and his eyes still water! In this example, the unconditioned stimulus is the______
a. fresh cut onions
b. ham sandwiches
c. watery eyes
d. kitchen