Based on the description, if the graph shows the percentage of sunlight remaining versus depth in meters, the sunlight visibility at a depth of 50 meters would likely be quite low. Typically, at significant depths like 50 meters, very little to no sunlight penetrates.
The correct estimation for the amount of sunlight that should be visible at a depth of 50 meters would likely be:
0%
This estimation aligns with the understanding that sunlight diminishes significantly in deep water.