Which statement about hydraulic jacks is true? 
 Which statement about hydraulic jacks is true? 
The Answer Is B
A. 
They multiply a force by making a gas flow through a valve. 
B. 
They multiply a force by transmitting it through oil. 
C. 
The forces at the input and the output are the same. 
D. 
The output pressure is much greater than the input pressure.