Concept:Tropism is the directional growth of a plant in response to an external stimulus such as light, touch, gravity, or moisture.
Explanation:The diagram illustrates a plant shoot bending and growing towards a unidirectional light source.
This directional growth movement in response to light is known as phototropism.
Since the shoot grows towards the light, it demonstrates positive phototropism.
Phototropism enables plants to position their leaves for maximum sunlight absorption during photosynthesis.
Thigmotropism is a growth response to touch, as seen when tendrils coil around a support.
Geotropism is a growth response to gravity, making roots grow downward and shoots grow upward.
Hydrotropism is a growth response to water or moisture gradients, usually shown by roots bending towards damp soil.
None of these other tropisms matches the shoot curving towards the light in the diagram.
Answer:B. Phototropism
