Which situation CANNOT be represented by this equation? -1/3x + 15 = 9

Athe water level in a tank measures 15 inches and is decreasing every 1/3 of a minute. At what rate, x, does the water level need to decrease per minute to reach a depth of 9 ft?

Bthe water level in a tank measures 9 inches and is rising 1/3 of an inch every minute. How many minutes, x, will it take for the water level to measure 15 inches deep?

Cthe water level in a tank measures 15 inches and is decreasing 1/3 of and inch every minute. How many minutes, x, will it take for the water level to measure 9 inches deep?