A two-dimensional incompressible frictionless flow field is given by $\overrightarrow{u} = x \hat{i} – y \hat{j}$. If $\rho$ is the density of the fluid, the expression for pressure gradient vector at any point in the flow field is given as

- $\rho(x \hat{i}+y \hat{j})$
- $ – \rho(x \hat{i}+y \hat{j})$
- $\rho(x \hat{i} – y \hat{j})$
- $ – \rho(x^2 \hat{i}+y^2 \hat{j})$