C - Show her father she can move as fast as a blue racer.
Explanation:
The lines "My father pulls my hand and leads me past the white scar of a snake carved into rotting growth. "If you can't go as fast as a Blue Racer," he says, "the next best thing is playing dead." before she runs off to prove that she can be as fast, her father providing the motive to do so. She shows no fear of it by running straight away, does not show any motive of wanting to keep it as a pet, and does not show any signs of being tired. This is the answer that makes the most sense, in my eyes.
A) get far away from the snake because she is afraid of it.
Explanation:
The author runs to get far away because she is scared of it. In the passage it states "My father pulls my hand and leads me past the white scar of a snake carved into rotting growth" and "My hand slips from his, and I run faster, faster, faster" supports the answer is A.