The 2nd and 3rd choices are the only correct ones.
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The rate of increase slows once there are more than 250 employees. (The nature of a "logistic function" such as this is that it is (approximately) exponentially increasing until half the "carrying capacity" of the resource, then is exponentially decreasing as it approaches the limit.)
When x=0, you have 500/(1 +19) = 25. The initial value is 25, not 20.
