You are the project manager for software development project. The feasibility study can start any time and takes 1 week and requirement gathering takes 2 weeks which can start only after feasibility study. The design and test plan development can start in parallel after the requirements gathering. Test plan preparation takes 8 weeks followed by a review by the customer and the time estimated for review is 1 week. After the review, Test data preparation takes 6 weeks. Design takes 6 weeks and it is followed by development and unit testing, for one module it takes 2 weeks and for the other module it takes 2 weeks. There are no dependencies between modules and they can be developed simultaneously. After test data preparation and development and unit testing of both the modules, there is 2 weeks system testing. What is duration of the critical path ？（）
A．14 weeks
B．15 weeks
C．20 weeks
D．19 weeks
