The organ which is sensitive to light in euglena is the

Explanation

Eyespot, also called stigma, a heavily pigmented region in certain one-celled organisms that apparently functions in light reception. The term is also applied to certain light-sensitive cells in the epidermis (skin) of some invertebrate animals (e.g., worms, starfishes). In the green one-celled organism, Euglena, the eyespot is light-sensitive region located in the gullet, at the base of the flagellum (a whiplike locomotory structure). It helps the euglena find bright areas to gather sunlight to make their food.