Final answer:
The closest estimation of the population parameter for a population size of 100,000 cases is d. 1000.
Step-by-step explanation:
Population parameter refers to the true value of a characteristic of a population. In this case, we have a population of 100,000 cases. The closest estimation of the population parameter depends on the degrees of freedom, which is determined by the sample size.
In statistics, larger degrees of freedom lead to a more accurate estimation of the population parameter. Since the population size is 100,000, the closest estimation of the population parameter would be for a larger degree of freedom. Among the options provided, the closest estimation would be the largest degree of freedom, which is d. 1000.
Therefore, option d. 1000 is the closest estimation of the population parameter for a population size of 100,000 cases.