Right choice is (a) Slushing
For explanation I would say: The separation of all the fibers from one another and their dispersion in water is called slushing or repulping. In the papermaking process utilizing purchased pulps and waste paper which are received as dry sheets, the first step is the separation of all the fibers from one another, and their dispersion in water with a minimum of mechanical work to avoid altering the fiber properties. This process is known as slushing or repulping and is carried out in a machine such as the hydrapulper, so called because of the hydraulic forces that are developed. When the pulping and papermaking operations are adjacent to one another, pulps are usually delivered to the paper mill in slush form directly from the pulping operation.