Here's a problem to solve: How do the sprouts of seeds buried in complete dark in the soil find their way to the surface of the soil?

Among the 4 following options, which is the correct answer?

- A: They grow toward light.
 
- B: They grow toward surface warmth.
 
- C: They grow opposite the direction of the bedrock.
 
- D: They grow opposite the direction of the pull of gravity.
 