In the Late 1870s,Charles Darwin and His Son Francis Discovered

Multiple Choice

In the late 1870s,Charles Darwin and his son Francis discovered that if the tip of the grass was covered,phototropism did not occur,even though the rest of the grass was exposed to light.However,if the rest of the plant was covered and only the tip exposed to light,the grass bent a few centimeters below the tip.Which of the following was sensing the light?

A) auxin-producing cells in the tip of the grass
B) auxin-detecting cells in the tip of the grass
C) auxin-producing cells a few centimeters below the tip of the grass
D) auxin-detecting cells a few centimeters below the tip of the grass