Explanation
In a large-scale project with unclear requirements, a fixed deadline, and a fixed budget, the project manager should adopt an agile approach that allows for flexibility, feedback, and collaboration. The project manager should agree with the client on a minimum viable product (MVP), which is the smallest version of the product that can deliver value to the customer. The project manager should also establish deadlines for review, where the client can provide feedback and prioritize the features for the next iteration. The project manager should run the project with a backlog, which is a list of features and requirements that are prioritized and refined by the team, and weekly sprints, which are short cycles of work where the team delivers a potentially shippable product increment. This way, the project manager can manage the project scope, schedule, and cost effectively, and deliver a product that meets the customer's needs and expectations. Option A is the best answer because it follows the agile principles and practices that are suitable for this type of project. Option B is not a good answer because it shows a lack of professionalism and responsibility from the project manager.
Option C is not a good answer because it may not be feasible or realistic to convince the client to provide a product owner, and it may delay the start of the project. Option D is not a good answer because it follows a traditional approach that is not suitable for this type of project, as it assumes that the requirements are clear and stable, and does not allow for frequent feedback and changes. References: [Agile Practice Guide], pages
14-15, 21, 25-26; [A Guide to the Project Management Body of Knowledge (PMBOK Guide)], Sixth Edition, pages 18-19, 174-175.