The correct option is C 20.5
In inclusive form class limits are obtained by subtracting 0.5 from lower limit and adding 0.5 to the upper limit.
∴ class limits of 10 - 20 class
interval in inclusive form are 9.5 - 20.5.
so, upper class limit of 9.5 - 20.5 is 20.5
∴ Option C is correct.