Adog experiencing a high level of fear will usually exhibit
a. ears lifted up and forward, direct eye contact, and hackles up.
b. ears pinned back, direct eye contact, and hackles up.
c. ears lifted up and forward, eyes averted or lowered, lips pulled back and down. d. ears pinned back, eyes averted or lowered, and lips pulled back and down.

I believe the correct answer is D. ears pinned back, eyes averted or lowered, and lips pulled back and down.
When dogs are afraid, their ears are lowered to show fear because of something they may have done wrong. They are also scared or embarrassed to look at their owner because they know they will receive some sort of punishment. Their tail is also usually tucked between their legs to show they are afraid.

Cells of an organism tell each other when predators are near.