To find the speed of the seagull, we can use the formula for speed:
\[ \text{Speed} = \frac{\text{Distance}}{\text{Time}} \]
In this case, the distance the seagull falls is 55 meters, and the time taken is 6.5 seconds.
Substituting the values into the formula:
\[ \text{Speed} = \frac{55 \text{ m}}{6.5 \text{ s}} \approx 8.46 \text{ m/s} \]
Rounding this to one decimal place gives a speed of approximately 8.5 m/s.
Thus, the correct response is 8.5 meters per second.