D If someone assigned you a task to configure the Firewall, you as a technician don't magically know where exactly in the network the Firewall has been placed. Especially considering you did not plan for and install the device yourself. You would need to refer to the physical and logical diagram to determine where the Firewall is in the network layout to be able to proceed with configuring it properly. You might be able to puzzle this out by examining rack diagrams and MDF/IDF documentation, but that to me seems to be the wrong way to go about it. Only once everything is configured would you then take your baselines.

Had to be D

D because you need to configure ports, route , vlans, sip, etcc. o establish the expected baseline then establish a new baseline

If the hardware is already racked, stacked, powered, and connected... then you don't need "A. Rack Diagram", "B. IDF/MDF documentation", or "D. Logical and Physical Diagrams"... it's already put in and connected! You couldn't have connected it without a logical or physical diagram! So I think C is the best answer... you need to start using it, and that starts with a "Network Performance Baseline", so C, not D.