Duration Matching in Fixed Income for Liabilities

John is a fixed-income portfolio manager who is focused on implementing a liability-driven investment strategy for a pension fund. The fund has a series of future cash outflows scheduled over the next 10 years due to retiree benefit payments. To ensure that he can meet these obligations without taking on excessive risk, John decides to utilize a duration matching strategy. He is considering several bond portfolios with varying characteristics.

John's objective is to align the duration of his bond portfolio with the duration of the liabilities to minimize interest rate risk. After conducting his analysis, he identifies three different bonds with the following durations:

• Bond X: Duration of 5 years
• Bond Y: Duration of 7 years
• Bond Z: Duration of 10 years

Based on this information, which bond should John select to best match the duration of the pension fund's liabilities?