Answer:
B. Tell the Senior Manager you will bring the materials as soon as you can.
Step-by-step explanation:
Both the individuals are important and require your dedication to the work they give, how trivial it may be. The manager will make a report of your work and will help you in the future with your troubles. The senior manager is the boss and your affirmation to her orders is vital for your success in the firm. Hence, you asses the situation according to the urgency of the work required. The assignment given by the Manager is need urgently but there is no urgency show the Senior manager.
Thus you can deliver the material as soon as you are done with the assignment, as soon as you are done.