What are the disadvantages of prototyping

Question

Problem:

Question 1- Which of the following variables is part of the ROI analysis?

1. Estimated opportunity costs
2. Estimated lifetime benefits
3. Estimated lifetime costs
4. Both estimated lifetime benefits and estimated lifetime costs
5. Both the discount rate and the number of years

Question 2- Which of the following is a disadvantage of prototyping?

1. Prototyping encourages a return to the "code, implement, and repair" life cycle.
2. Prototypes are a passive model of the system.
3. End users don't fully understand their requirements until they see them implemented.
4. Errors cannot be detected as easily when a prototype is developed.
5. None of the above

Please select correct answer and also provide explaination.