Which information are necessary to answer the questions asked- What is the length of the train X? I. Two trains X and Y running in opposite directions and cross each other in 25 seconds. II. The length of the train Y is 320m and the difference between the speeds of trains X and Y is 14 km/h. III. The ratio of the speed of the trains is 19:26.

Using all three statements: Speeds are in ratio 19:26, let them be 19k and 26k km/h. Speed difference = 7k = 14, so k=2. Speeds: 38 km/h and 52 km/h. Relative speed in opposite direction = 90 km/h = 25 m/s. Crossing time 25s = (Lx + 320)/25, so Lx = 25×25 - 320 = 625-320 = 305m. All three together ARE sufficient, but options A-D are incorrect. E is correct as 'None of these'.