Answer:
1 × 10^3 feet
Step-by-step explanation:
1 × 10⁻⁸ feet = 0.00000001 feet
1 × 10⁻³ feet = 0.001 feet
1 × 10³ feet = 1000 feet

So,

1 × 10⁸ = 100000000

The first two are less than 1 feet.
The last one is very high to put it into context the tallest building (Burj Khalifa) is 1,918 feet.
So, the third one is the most acceptable.