A fish is swimming at a constant rate toward the ocean floor. The equation y=-7x-3 can be used to represent this situation, where y is the depth of the fish in meters below sea level and x is the number of seconds the fish has been swimming. Which statement best describes the depth of the fish, given this equation?
A. From a starting point of 7 meters below sea level, the fish is descending 3 meters per second.
B. From a starting point of 7 meters below sea level, the fish ascending 3 meters per second.
C. From a starting point of 3 meters below sea level, the fish is descending 7 meters per second.
D. From a starting point of 3 meters below sea level, the fish is ascending 7 meters per second.
