You can see my previous answer to this very same question on https://brainly.com/question/11374210.
The answer is: option D. Response to environment.
Explanation:
As explained, plants (organisms in general) respond to the stimulus provided by the environment.
Such behavior is named tropism. Tropism may be positive or negative.
When the plant's stem bends toward the window, it is showing positive phototropism, which means that the plant growth response to light such that the stems bend toward light, permiting the leaves to receive more light.
I also mention that while the plant's stems posses positive phototropism they posses negative gravitropism and the roots posses positive gravitropism.
Gravitropism is the response of the plant growth to gravity.
Stems grow away from gravity meaning that this is negative gravitropism, but roots grow toward gravity which is positive gravitropism