In a photo-tropic experiment, young seedlings in a box were subjected to light from one direction. The seedling continue to grow erect. Which of the following statement is correct

• A.Only the tip of the seedling received the light
• B.The light was not strong enough
• C.The seedlings were rather too young
• D.The tip of the seedling may have been covered
• E.The box containing the seedling should have been placed on a laboratory bench