Correct Answer - b
As, `B = ("normal stress")/("volumetric strain") = (Delta P)/(-Delta V//V)`
Here, negative sign shows that volume is decreased when pressure is increased.
Here. `B = 2100 xx 10^(6) Pa, V = 200 L`
`Delta V = 200 xx (0.004)/(100) = 0.008 L`
`:. 2100 xx 10^(6) = (Delta P)/(((0.008)/(200)))`
`:. Delta P = 84 kPa`