Answer:
correct option is C i.e. 25 km/hr
Step-by-step explanation:
given data:
Initial velocity u = 10 km /h 
acceleration a = 30 km/h^2 
 time = 30 min = 1/2 hr
we know from equation of motion, final velcoity is given as
final velocity = initial velocity + at
v = u + at
 putting all value from above to get the final velocity value
 v = 10 + 30* (1/2) 
 v = 25 km/hr
 so correct option is C i.e. 25 km/hr