Consider the following velocity field: $V=\{-2$axy$\}i+a\{y^2-x^2\}j.$ Neglect the gravitational effect. Determine under what conditions it is a solution to the Navier$-$Stokes momentum equation.

a$.$ del$\frac{P}{d}$elx$=-4a^2(x{y}^2+3x^3)$;del$\frac{P}{d}$ely$=-4a^2(x^{2}y+3y^3)$

b$.$ del$\frac{P}{d}$elx$=-2a^2(x{y}^2+x^3)$;del$\frac{P}{d}$ely$=-2a^2(x^{2}y+y^3)$

c$.$ del$\frac{P}{d}$elx$=-8a^2(x{y}^2+2x^3)$;del$\frac{P}{d}$ely$=-8a^2(x^{2}y+2y^3)$

d$.$ del$\frac{P}{d}$elx$=-2a^2(2x{y}^2+x^3)$;del$\frac{P}{d}$ely$=-2a^2(x^{2}y+2y^3)$