The curve amongst the family of curves, represented by the differential equation, (x2−y2)dx+2xydy=0 which passes through (1,1) is : [JEE-MAIN ONLINE-2019]
1. A circle with centre on the y-axis
2. A circle with centre on the x-axis
3. An ellipse with major axis along the y-axis
4. A hyperbola with transverse axis along the x-axis