What is the substance called that coats the lungs and keeps the air sacs in the lungs from collapsing?

One factor in hunger seems to be the increase in ________, which causes blood sugar levels to eventually drop several hours after we eat

a) cholesterol b) lipoproteins c) insulin d) glucose

Computer systems that are intended to mimic the human brain are called __________

a) expert systems. b) artificial neural networks. c) robots. d) cyborgs.