Given no other restrictions, what are the domain and range of the following function?
f(x) = x^2 - 2x + 1
a. d = all real numbers
r = all real numbers
b. d = all real numbers
r = {y | y > - 1}
c. d = all real numbers
r = {y | y > 0}
d. d = {x | x > 0}
r = {y | y < 1}