a. The height of the red line shows the amount of individuals in the population at that specific period of time. So, when the red line is drawing a line that goes up and gets really high in a small period of time, this is when the population is growing at its fastest rate. Therefore, it is number 2.
b. the carrying capacity refers to the maximum of individuals that a specific environment can handle. The graph will always show the carrying capacity as a point in which the curve stop going up and get estabilized, with smal fluctuations only. In this case, we see a first point in which there are fluctuations after the fastest rate of growth, and later we see that the line gets a little bit lower but repeat this pattern of small fluctuations again, showing that the carrying capacity has declined. Therefore, it is number 4.
c. As explained above, the population first reaches its carrying capacity when the curve stop going up and get estabilized, with smal fluctuations only. This happens at the point number 3.