Leaves curving towards sunlight are examples of
phototrophism
geotrophism
thigmotrophism
hydrotrophism

The correct answer is phototrophism.

Phototrophism is said to be the growth of a plant toward a source of light.

It is response to the stimulus of  light and is seen when a plant bends towards the direction that light is coming from. Response by plants to a stimulus is called tropism. The  word or prefix "photo" means or refers to light. Therefore phototropism simply means response to light.

Phototropism can be especially evident in the jungle where the jungle floor gets very little light. If a tall tree falls to the ground, it leaves a gap in the canopy through which sunlight streams to the ground. Many jungle plants growing on the ground will bend towards the  gap  and rapidly grow towards the source of  light.