Answer:
Option (a)
Step-by-step explanation:
Let c be the specific heat of water.
According to the principle of caloriemetry.
Heat lost by hot water = heat gained by cold water
200 x c x (70 - T) = 50 x c x (T - 20)
280 - 4T = T - 20
300 = 5T
T = 60 C