If f(x)=ax2+bx+cf(x) = ax^2 + bx + cf(x)=ax2+bx+c and f(f(x))=xf(f(x)) = xf(f(x))=x, which of the following is true?
a=1,b=0,c=0a=1, b=0, c=0a=1,b=0,c=0
a=0,b=1,c=0a=0, b=1, c=0a=0,b=1,c=0
a=0,b=−1,c=0a=0, b=-1, c=0a=0,b=−1,c=0
a=−1,b=1,c=0a=-1, b=1, c=0a=−1,b=1,c=0