To find the time when the volleyball reaches its maximum height, we can use the vertex formula for a quadratic function in the form of \( h = -16t^2 + 33t + 6 \), which is in the standard form \( h = at^2 + bt + c \).
The time \( t \) at which the maximum height occurs for a parabola given by \( h = at^2 + bt + c \) is found using the formula:
\[ t = -\frac{b}{2a} \]
Here:
- \( a = -16 \)
- \( b = 33 \)
Plugging in these values:
\[ t = -\frac{33}{2 \times -16} = \frac{33}{32} \approx 1.03 \text{ seconds} \]
Thus, the domain of the ball when it reaches its maximum height is approximately 1.03 seconds.
So, the correct response among the options provided is:
1.03 seconds.