People often think closing an unused credit card is a simple “clean-up” step. But accounts on your credit report contribute to available credit, and closing a card reduces your total credit limit while leaving outstanding balances unchanged — that combination raises your overall credit utilization percentage, which can lower your score. Additionally, older accounts help the “length of credit history” factor; closing a long-held card doesn’t remove its history but may change how average age is calculated if it’s later removed for inactivity. If your goal is to improve your credit score quickly, smaller steps like paying down balances or moving balances strategically before closing accounts tend to be more effective than an immediate close. The question asks which action is most likely to increase utilization and potentially harm your score.