Which of the following factors is a consideration in design for maintainability?

The correct answer is A. Frequency of scheduled servicing . In the CSSBB DFSS and maintainability material, maintainability is associated with designing products so they can be easily serviced, repaired, restored, and kept available. The CSSBB source lists maintainability-related guidelines such as standardization , modularization , accessibility , fault isolation , interchangeability , and methods of recording corrective and preventive maintenance . These considerations are all tied to how easily and efficiently the product can be maintained over its life.

Among the answer choices, the factor that best fits maintainability thinking is the frequency of scheduled servicing , because maintainability addresses how often service is needed and how easily that service can be performed. Product failure modes are more directly associated with reliability and FMEA. Variability of process inputs relates more to robust design and process capability. Number of customer complaints is an outcome metric, not a design-for-maintainability factor. Since maintainability focuses on serviceability and ongoing upkeep, the best CSSBB-based answer is A. Frequency of scheduled servicing .