Which of the following statements is/are false? 

• A. To prevent heat generated due to friction, rope brake dynamometers are provided with cooling water
• B. Angle of twist upto 1/10 of degree can be measured by Glibson flash light torsion dynamometer
• C. In pneumatic brakes, the ratio between hydraulic pressure and air pressure is 15:1
• D. All the above statements are false