It's important to communicate such information to the team promptly, and the daily standup is a suitable forum for sharing updates and potential impacts on the project.
By informing the team during the standup, the project manager can ensure that everyone is aware of the situation and can collectively discuss how to manage the workload and any potential risks. While options A, C, and D may be relevant, immediate communication with the team is crucial to maintaining transparency and allowing the team to adjust to the changes in personnel. After the team is informed, the project manager can then consider discussing with the functional manager and addressing any potential delivery delays or developing a mitigation strategy.