Which primary area should an administrator consider to ensure adequate airflow and to provide space for
servicing of servers in a data center?

A.
the space of the sides of the rack

B.
the space above and below the rack

C.
the space between adjacent racks

D.
the space in front and behind the rack

Explanation:

Example of HP recommendations:
Space and airflow requirements
To allow for servicing and adequate airflow, observe the following space and airflow requirements when deciding where to install a rack:
Leave a minimum clearance of 63.5 cm (25 in) in front of the rack.
Leave a minimum clearance of 76.2 cm (30 in) behind the rack.
Leave a minimum clearance of 121.9 cm (48 in) from the back of the rack to the back of another rack or row of racks.
References: http://h17007.www1.hpe.com/docs/iss/DL380pGen8/setup_install/advanced/Content/40851.htm