7) B

Only the first digit (8) was faulty and three lights were permanently on.

So we need to look at which numbers can be formed from 8. 

0 can be formed if we take out 1 light from 8.
2 can be formed if we take out 3 lights from 8.
5 can be formed if we take out 3 lights from 8.
6 can be formed if we take out 3 lights from 8.
9 can be formed if we take out 3 lights from 8.

However, the maximum score is 505. 

So the actual score could have been:

005
205

It could not have been 505, 605 or 905.

There could have been 2 different values for the actual score.

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