Consider the following statements about the quadratic graph $y = ax^2 + bx + c$: Which of the following is correct?

1. The graph is parabolic.
2. The graph has an axis of symmetry parallel to the y-axis.
3. The function has a maximum or minimum value at a certain point.

• ai and ii
• bii and iii
• ci and iii
• di, ii and iii