Consider a model of finite control volume (volume V and surface area) fixed in space with elemental volume dV, vector elemental surface area d ( vec{S} ), density and flow velocity ( vec{V} ). What is the mass inside the control volume?

• A. ( iint_s rho vec{V}.d vec{S} )
• B. ( iiint_V rho dV )
• C. dV
• D. ( frac{ partial}{ partial t} iiint_V rho dV )