The general solution of x (1+y^{2} )^{1 / 2} d x+y (1+x^{2} )^{1 / 2} d y=0 is

Correct Answer is : (1+x2)12+(1+y2)12=c

x^{2}+y^{2}= (1+x^{2} )^{1 / 2}+ (1+y^{2} )^{1 / 2}+c

(1+x^{2} )^{1 / 2}+ (1+y^{2} )^{1 / 2}=c