An airplane is landing at Memphis International Airport. The airplane is currently flying at a height of 13,000 feet. The airplane begins its decent to the landing strip at a constant rate of 500 feet per second. The airplane will continue its constant decent until it lands. Write an expression to represent the airplane's decent until it lands.
A) 13000+500s
B) -500s +13000
C) 13000-26s
D) 26s+13000