The correct answer is D) the number of years that you have used your credit responsibly.
The factor that has the biggest impact on credit score is the number of years that you have used your credit responsibly.
The most important factor in your credit score in your payment history. That is number one and you must have a good credit history to have good finances. If you miss a payment, it could have consequences on your credit score. Never have late payments in your credit card. That affect your score so much.
