1. The problem asks to determine the axis of symmetry for a parabola that opens upward and has its vertex at (0, -4). 2. The axis of symmetry of a parabola is a vertical line that passes through the vertex. 3. Since the vertex is at (0, -4), the axis of symmetry is the vertical line passing through $x=0$. 4. Therefore, the axis of symmetry is given by the equation: $$x=0$$ 5. This matches option B.