P0, P1, P2 be the populations of a city at times t0, t1 and t2 = 2t1, the saturation value of the population Ps of the city, is

• A. <img src="/_files/images/civil-engineering/water-supply-engineering/204-10.30-1.png">
• B. <img src="/_files/images/civil-engineering/water-supply-engineering/204-10.30-2.png">
• C. <img src="/_files/images/civil-engineering/water-supply-engineering/204-10.30-3.png">
• D. <img src="/_files/images/civil-engineering/water-supply-engineering/204-10.30-4.png">
• E. None of these.