I Am Sitting in a Movie Theater and It Dawns

I am sitting in a movie theater and it dawns on me that there are many things that I could be paying attention to but somehow I ignore that which is unimportant and stick to that which is relevant. This capability is thought to be due to:

A) signals from the reticular formation to the thalamus
B) signals from the cortex and the thalamus
C) pons and medulla
D) amygdala and hippocampus