Which scenario would result in the highest NPV?

• 75% retention rate, a 10% required rate of return and the same customer profit in years 1-4
• 75% retention rate, a 10% required rate of return and the same customer in years 1-7
• 50% retention rate, a 50% required rate of return and the same customer in years 1-4
• 50% retention rate, a 10% required rate of return and the same customer in years 1-7