Explanation
According to the PMBOK Guide 7th Edition, the project manager should act as a facilitator and coach in an agile environment, which means supporting the team members in their self-organization, collaboration, and decision making. The project manager should also respect the team's autonomy and empower them to deliver value. Therefore, the best option is to allow the team to decide on their own which option should be implemented, based on the results of the spikes. Asking the project sponsor, organizing a multivoting event, or organizing more spike events are possible actions that the project manager can take later, but they are not the best option to support the team in their agile approach. References: PMBOK Guide 7th Ed., 2.0 The Project Delivery Principles, Page 9; PMBOK Guide 7th Ed., 3.0 The Project Team, Page 23; 1