A sophisticated client, managing a taxable account, seeks to invest a portion of their portfolio to fund a future liability in 15 years. Their primary objective is to preserve the real purchasing power of this investment against inflation, while also minimizing exposure to market price volatility caused by changes in interest rates. They are evaluating a purchase of either 15-year Treasury Inflation-Protected Securities (TIPS) or 15-year U.S. Treasury STRIPS. Which statement most accurately describes a key characteristic relevant to managing market price volatility and purchasing power for this client's Series 7 objective?