Concept: The question tests on the basics of  Rates(Speed and Time)

Solution:

Since distance is a constant, we have that s1 * t1 = s2 * t2

s1 = 60 km/hr, t1 = 50 minutes, s2 = s and t2 = 60% of 50 minutes = 30 minutes

Therefore 50 * 60 = s * 30

s = (50 * 60) / 30 = 100 km/h


Option D