【单选题】

Transfer of hydraulic fluid between hydraulic system A and B is caused by improper operation of system controls or worn equipment.

A、Uncontrolled system or old equipment cause hydraulic fluid flow from hydraulic system A to B.
B、If you fail to operate the system control properly or the equipment is damaged, the hydraulic fluid will be transferred between hydraulic system A and B.
C、Flow of hydraulic fluid between hydraulic system A and B result in accidental operation of system controls or damaged equipment.