The movement of the sunflower by the path of the sun is due to
(a) phototropism
(b) geotropism
(c) chemotropism
(d) hydrotropism
Explanation: Tropism is growth towards an external stimulus. It is of different types. In phototropism, the growth of plants is towards the direction of light. Thus, the movement of the sunflower by the path of the sun is due to phototropism. Hence, (a) is the correct option.