For a certain two-dimensional incompressible flow, velocity field is given by $2xy\hat{i}-y^2\hat{j}$ . The streamlines for this flow are given by the family of curves

- $x^2y^2 = \text{constant}$
- $xy^2 = \text{constant}$
- $2xy − y^2 \text{constant}$
- $xy = \text{constant}$