We can eliminate answer choices by looking at several factors. If the parabola opens upward, there cannot be a negative number as 'a'. Recall that standard form of a parabola is y= ax² + bx + c.
Therefore, any choice that has a negative number as 'a' opens downward. This leaves answers A and C.
Next, for the parabola to appear narrower, it must have some kind of vertical stretch or horizontal compression. 'A' is the only choice that has a vertical stretch transformation done to the parabola. The correct answer is A.
A parabola opening up will have a positive value for the a value in ax^2+bx+c form. Also, the larger the absolute value of the a value, the more narrow the parabola will appear.
