Answer: f(f(x))=x^4+2x^2+2
Step-by-step explanation:
f(x)=x^2+1
f(f(x))=(x^2+1)^2+1
f(f(x))=(x^2+1)(x^2+1)+1
f(f(x))=x^4+x^2+x^2+1+1
f(f(x))=x^4+2x^2+2 ==> 2nd option
