Doug plants a few peas. After two days, he sees the shoot and the root forming. He observes that the shoot grows upward, toward the light. The root grows downward, into the soil. Why do these embryonic organs grow in a specific direction?

The shoot is positively phototropic and positively gravitropic; the root is positively phototropic and positively gravitropic.
The shoot is positively phototropic and negatively gravitropic; the root is positively gravitropic and negatively phototropic.
The shoot is positively gravitropic and negatively phototropic; the root is positively phototropic and negatively gravitropic.