The movement of a sunflower facing the sun is called:

Correct option is C

The correct answer is phototropism.

• Phototropism is a directed response in plants that permits them to grow towards, or away from, a light source.

Information Booster:

• The modulation of physiology or development in relation to day length is known as photoperiodism.
• Positive phototropism is the plant's reaction to the light source.
• Sunflower is an example.
• Negative phototropism occurs when a plant grows in the opposite direction of the light source.