<span>the answer is
C. The bar for very low concentration is twice the height of the bar for medium concentration.
proof
</span>
<span>
</span>
<span>Medium--------------------15
</span>Very Low-------------------30 = 2<span /> x 15 (<span>Medium)
</span>
When this happens, light changes speed and the light ray bends, either toward or away from what we call the normal line, an imaginary straight line that runs perpendicular to the surface of the object.
