Graph y=x^2+1 is it a function is it a function? how did you determine whether or not it was a function? determine the range and domain

Hello,

The graph of y = x² + 1 most certainly is a function. 
It is a function because for every value of x, there is only one value of y. 

The domain of y = x² + 1 is the set of all real numbers and the range is y ≥ 1. 

Ithink it is b and d