$[1$ marks$]$ Which statement is true:

A$.$ Continuum assumption implies that solids and fluids can deform under shear stress

B$.$ Continuum assumption entails that fluids are built up from very tiny continuous particles

C$.$ Continuum assumption means that solids are very small infinitely divisible

D$.$ Continuum assumption implies that fluids can deform under shear stress

$[1$ marks$]$ A major difference between hydrodynamics and gas dynamics is:

A$.$ in hydrodynamics the volume is constant, but in gas dynamics fluids have reduced volume up to $20-30\%$ of the original

B$.$ hydrodynamics deals with fluids of variable density, but in gas dynamics the density is constant

C$.$ hydrodynamics deals primarily with fluids of constant density, but in gas dynamics the density is changing

D$.$ the field of hydrodynamics is liquids while that of gas dynamics is gases

$[1$ marks$]$ Which statement is true:

A$.$ Solids and fluids have densities that are sometimes close to each other

B$.$ Solids densities are always larger than those of fluids

C$.$ Solids densities are always smaller than those of fluids

D$.$ Solids and fluids densities cannot be compared to each other