Final answer:
The end behavior of a polynomial function can be determined by looking at the leading term. If it has a positive coefficient and an even degree, then as x approaches positive or negative infinity, y approaches positive infinity.
Step-by-step explanation:
The end behavior of a polynomial function describes the behavior of the function as x approaches positive or negative infinity. To determine the end behavior, we look at the leading term of the polynomial, which is the term with the highest degree. If the leading term has a positive coefficient and an even degree, then as x approaches positive or negative infinity, y approaches positive infinity. This corresponds to option D, As x approaches infinity, y approaches infinity.