to reduce the amount of work for all involved to reduce the cost of conducting experiments on people to obtain results quickly in a short period of time to perform experiments that would be irresponsible using human subjects
I gave my students this multiple choice question: Scientists often use mathematical models and computer simulations to study systems. What is the main advantage of using these techniques for studying the spread of infectious diseases?

Only one answer is correct among these 4 choices:
- to reduce the amount of work for all involved
- to reduce the cost of conducting experiments on people
- to obtain results quickly in a short period of time
- to perform experiments that would be irresponsible using human subjects

Could you tell me which one is correct?

to perform experiments that would be irresponsible using human subjects