What is the minimum total duration between the Milestones A and B?

This is a question from oliver lehman free questions. The answer is 37 days. Am not sure how to arrive at this answer . Please let me know if any of you are able to get this right.

2) Your manager is assessing an international investment, for which he asks you to estimate

the rate which occurs as the present value of the cash inflows equals to that of the cash

outflows. Which of the following is used by your manager to assess this investment?

1. Internal rate of return 

2. Net present value

3. Opportunity cost

4. Discount rate 

IS the answer to this 1 or 4 as i have seen two different sources with answer 1 and another saying its answer 4 

3)ORGANIZATION A commissions ORGANIZATION B to develop a project, and ORGANIZATION

B sub-contracts to ORGANIZATION C. One day, ORGANIZATION A's project manager thinks

there are problems with the orders being carried out by ORGANIZATION C's project team

members and orders them to stop work. What should the project team members of

ORGANIZATION C do?

1. Coordinate and communicate with the project manager of ORGANIZATION B. 

2. All of these statement are true.

3. Carry on with their work.

4. Ask the project manager of ORGANIZATION A to propose a change requests.

I thought the answer to this is 3 but another source told me that the answer is 1 . Which one of these is true .

Any pointers with explanations to these questions would be great  .

Thanks ,

Hari 

42 days