To find the time at which the volleyball reaches its maximum height, we need to use the formula for the vertex of a parabola represented by the quadratic function \( h = -16t^2 + 33t + 6 \). The vertex is found at \( t = \frac{-b}{2a} \), where \( a \) is the coefficient of \( t^2 \) and \( b \) is the coefficient of \( t \).
In this case:
- \( a = -16 \)
- \( b = 33 \)
Plugging these values into the formula gives us:
\[ t = \frac{-b}{2a} = \frac{-33}{2 \times -16} = \frac{33}{32} \approx 1.03 \text{ seconds} \]
Therefore, the answer that corresponds to when the volleyball reaches its maximum height is 1.03 seconds.