Final answer:
For a married couple with high credit card balances, paying down their credit card debts is the most effective action to improve their credit score. This reduces their credit utilization and minimizes interest paid over time. New cards can increase debt, and closing a card affects credit utilization ratio.Option B is the correct answer.
Step-by-step explanation:
The action that would most likely have the greatest positive impact on the clients' credit score, considering they have three credit cards with high balances and a cash advance loan, would be B- Paying down their credit card balances. This is based on the information emphasizing the importance of not using too much of the credit that is available and paying off debts quickly to avoid high interest rates on the borrowed amounts. Continuously carrying a credit card balance from month to month results in accruing interest, which is costly in the long run.
Opening a new secured credit card or a department store charge card would pose a risk of increasing their overall credit utilization and potential debt, which could negatively impact their credit score. Paying off and closing one card could momentarily lower their available credit, which might negatively affect their credit utilization ratio, but it would not have as immediate or significant a positive impact as reducing overall debt levels.