The water molecules will flow from b to a due to osmosis.
Osmosis is where water molecules will flow from a region of higher water potential to a region of lower water potential, through a selectively permeable membrane.
When the water molecule concentration is higher, it has a higher water potential top. Water potential is the tendency for them to flow to a lower region.
The net movement will stop until both sides of the solution has a same water potential.
        
             
        
        
        
Bromine is a reddish-brown color.
Benzene is clear or colorless
        
                    
             
        
        
        
B. I’m sorry if I’m wrong ! Wasn’t sure about this question .