f is an even function, and g is an odd function, such that `f(x) +g(x)=e^x,` for all x. Then which is correct `(A)` `(f(x))^2 +(g(x))^2=1` `(B)` `(g(x))^2-(f(x))^2=1` `(C)` `(f(x))^2=(g(x))^2` `(D)` `(f(x))^2 =(g(x))^2+1`