Final answer:
Customer complaints are usually required to be kept for about seven years due to legal and regulatory reasons specific to an industry and jurisdiction.
Step-by-step explanation:
Retention of written customer complaints is typically governed by regulatory requirements, which dictate how long such documents should be kept. Although the exact duration can vary based on the industry and jurisdiction, a common period for keeping customer complaints is around seven years. This duration is often related to the statute of limitations for legal actions, potential audits, and other regulatory matters requiring historical records. It's essential for businesses to familiarize themselves with the specific regulations that apply to their industry and maintain compliance accordingly.