You and Your Friends Are Having a Sleepover

Multiple Choice

You and your friends are having a sleepover.One of the friends falls asleep and is snoring.The rest of you are talking loudly without waking her,but when you begin to make cookies,the smell jolts her from sleep immediately.How can this be?

A) The brain blocks out most stimuli even though it is processing the information; a good smell was worth attending to.
B) The brain can block out stimuli for only a limited time. The friend would have awakened even without the cookie smell.
C) Talking at any volume is soothing, so people can sleep through that but not the strangeness of baking.
D) The brain cannot block any stimuli from reaching the cortex; the friend waking was unrelated to the smell of cookies.