Which of the following actions is most likely to negatively impact an individual's credit score?

Closing out a well-established credit card account with a good payment history can negatively impact an individual's credit score for several reasons. One of the key factors affecting credit scores is the length of credit history; when a long-standing account is closed, it reduces the average age of accounts, which can lower the score. Additionally, closing a credit card decreases the overall available credit, which can increase the credit utilization ratio if other credit limits remain unchanged. A higher credit utilization ratio often correlates with a lower credit score, as it indicates a higher risk to lenders.

Furthermore, having a mix of credit types and maintaining use of established accounts also plays a role in credit scoring. Closing an account that has had a positive payment history erases that history from the scoring model, further harming the score. In contrast, other actions like paying off a revolving card balance or applying for loans at intervals do not carry the same direct negative implications on credit scores.