The correct answer is B.
OBJ-3.7.1: A daily log is used to record problems/concerns that can be handled by the project manager informally. A daily log may be used to record informal issues, required actions, or significant events not captured by other PRINCE2 registers or logs. It can act as the project diary for the project manager. It can also be used as a repository for issues and risks during the starting up a project process if the other registers have not been set up.