What is the domain of the function y = x2 - 4x + 3?

A domain represents all possible values of the independent variable in a given function. In this case, the function is a polynomial, which means it is defined for all real numbers. Therefore, the correct domain for this function is -∞ < x < ∞.

Option B is incorrect because it only includes values larger than -3, when in fact the function is also defined for values less than -3.

Option C and D are incorrect because they limit the domain to specific regions, -2 < x < 3 for option C and 0 < x < 3 for option D. These ranges do not cover all possible values of x for the given function.

Overall, the correct domain for this function is A because it includes all real numbers, whereas the other options limit the domain unnecessarily.