C.
Thanks me later, that's my answer.
1. Centimeter
2. Kilogram
3. Millisecond
4. DL
5. Kg
6. Mm
7. S
8. Mm
9. Us
Power = Work / time
The work given here is 83J and the time it took to do 83J of work was 3s
So..
Power = 83J / 3s
Power = 27.67 W or 27.7 W
Sound intensity = 1/(r^2)
That is Sound intensity is indirectly proportional to the distance. Therefore, sound becomes 9 times less intense.
