The possible answers are :
Answer 1 :After about 3 weeks, the population reached its carrying capacity of about 250 plants.
Answer 2 After about 4 weeks, the population reached its carrying capacity of about 225 plants.
Answer 3 The population did not reach its carrying capacity because it was still slowly increasing.
Answer 4 The population did not reach its carrying capacity because it was declining at the end of the experiment.
The correct answer is Answer 1
As we can see from the graph presented below, population 3 in this experiment with duckweed has been growing in an environment rich in nutrients and light. After 3 weeks of the experiment this population has reached a number of 250 individuals and stopped growing. This is a good indicator that this population has reached the limit of the carrying capacity of the environment.