In a syphilis infection, a chancre usually heals in

After Pavlov's dog heard the neutral stimulus of the bell rang alongside the unconditioned stimulus of the meat, the dog eventually drooled to the sound of the bell alone. The drooling to the ringing of the bell then became:

a. an unconditioned response. b. a conditioned response. c. a neutral stimulus d. a conditioned stimulus.

Archeologists found the first evidence of a group of hominids that seemed to live more in a city-type dwelling. They had previously only seen evidence of hunter-gatherer patterns of traveling and migrating

This first evidence was probably discovered in: a. Egypt b. North America c. China d. Southern Africa