Angle made by hour hand:
for 2 hours: 2*30 = 60
for 42 mins: (42/60) * 30 = 21
Total angle made by hour hand is: (60 + 21)= 81 degrees
Angle made by minute hand:
for 42 min: 42*6 = 252
Total angle made by minute hand is: 252 degrees
The angle between the minute and hour hand is: (252-81) = 171 degrees
My question is about "why is 171 degrees a wrong answer" and the correct answer is 189 degrees

Here is the right image of the clock. See the angle between hour and minute hand is measured in a counterclockwise manner, hence it is more than $180^{\circ}$.