Problem: a steel vessel has a base of length 60 cm and breadth 30 cm . water is poured in the vessel . a cubical steel box having edge of 30 cm is immersed completely in the vessel . how much will the water rise ? 
Options: ['a ) 7.5 cm rise', 'b ) 10 cm rise', 'c ) 15 cm rise', 'd ) 30 cm rise', 'e ) none of these']
c