Statement I : Every function must be either even or odd function Statement II : The function f(x)=log(x+x2+1) is an odd function Which of the following is true

I : is not true Ex :f(x)=x2+x+1 then f(−x)=x2−x+1≠f(x) or ≠−f(x) II : f(−x)=log((x2+1−x)x2+x+xx2+1+x)                  =−log(x+x2+1)=−f(x)     odd functiononly II is true