$($c$)($a$)$Q$16.$ N$-$S equation can be written in two ways given by $($a$)$ and $($b$)$ below,

$($a$)\frac{\text{d}\text{e}\text{l}}{\text{d}\text{e}\text{l}\text{t}}(vec(v)+$grad$*(vec(v)vec(v)))=vec(g)+$grad$*vec(T),$

$($b$)(\frac{\text{d}\text{e}\text{l}(vec(v))}{\text{d}\text{e}\text{l}\text{t}}+(vec(v))*grad(vec(v)))=vec(g)+$grad$*vec(vec(T)).$

Using Continuity equation show that $($a$)$ and $($b$)$ are equal.