What Causes the Hypocotyl of Dicots to Straighten

Question

What causes the hypocotyl of dicots to straighten?  
A) Light
B) Gravity
C) Wind
D) Earth's magnetic field
E) Soil

Accepted Answer

The hypocotyl of dicots straighten due to a process called phototropism, in which the plant grows towards a source of light. As the hypocotyl elongates, it will naturally curve towards the light. This response helps the plant to reach the surface of the soil where it can access light for photosynthesis.