Answer:
D. The number of employees of an insurance company.
Explanation:
The variable that measures the numbers such as height, number of people, shoe sizes is called the discrete quantitative variable. Therefore, option "D" is the answer. Anyone can measure the number of employees. It is not continuous process too.
The volume of water cannot be measured with a specific value, and the Dow Jones Industrial average is not a certain value. So, those options are incorrect either. Although Option "C" can be measured with a value, it cannot be interrupted and continuous process. Hence, it is also wrong.