The correct option is D Heliotropic chamber
Phototropism was first studied by Charles Darwin in 1880 in Canary Grass and oat coleoptiles. Later on F.W. Went in 1923, suggested the involvement of auxins in this phenomenon. Experimental approach to demonstrate positive phototropism in shoot tips is a darkened black box. The black box is having a small window at one side. A well-watered potted plant is placed inside the box. The is referred to as a phototropic chamber or heliotropic chamber. The window is kept closed for about 24 hours and the plant shows normal growth. If the window is kept opened, it is found after two days, that the shoot tip bends and grows towards light proving that it is positively phototropic.