If the stem grows towards sunlight and root grows just opposite to it, the stem movement us known as

The correct option is positive phototropic movement.

To understand why this is the correct answer, let us break down the concepts of plant growth movements:
1. Tropic Movements (Tropisms): These are directional growth movements in plants that occur in response to an external stimulus. The direction of the growth depends on the direction of the stimulus.
2. Phototropism: This is the growth of a plant or plant part in response to light (from the Greek words "photo" meaning light, and "tropos" meaning turn).
3. Direction of Response:
- Positive Tropism: Growth of a plant part towards the direction of the stimulus.
- Negative Tropism: Growth of a plant part away from (or opposite to) the stimulus.

Since the stem grows directly towards the source of sunlight, it is exhibiting growth in the direction of the light stimulus. Therefore, the movement of the stem is referred to as positive phototropic movement.
In contrast, because the root grows in the direction opposite to the sunlight, its movement is referred to as negative phototropic movement.