To find the speed at which Dandelion the cat is running, you can use the formula for speed:
\[ \text{Speed} = \frac{\text{Distance}}{\text{Time}} \]
In this case, the distance is 35 feet and the time is 0.8 seconds.
Calculating the speed:
\[ \text{Speed} = \frac{35 \text{ feet}}{0.8 \text{ seconds}} = 43.75 \text{ feet per second} \]
So, the correct answer is 43.75 feet per second.