Which of the following is a main operating expense category for data centers?

Cooling systems are a main operating expense category for data centers due to the critical need to maintain optimal temperature and humidity levels for the equipment housed within. Data centers typically contain numerous servers and networking equipment that generate significant heat during operation. To prevent overheating, effective cooling systems—such as air conditioning units, chilled water systems, and CRAC (Computer Room Air Conditioning) units—are essential for ensuring operational efficiency and longevity of the hardware.

While other expenses like marketing, real estate taxes, and advertising might be pertinent to general business operations, they do not directly relate to the specific operational functionality and requirements of a data center. The primary focus in data center management is on ensuring a stable and secure environment for the technology infrastructure, which solidifies cooling systems as a crucial operating expense.