Final answer:
The fraction of light bulbs that are working is 4/10.
Step-by-step explanation:
The best way to describe the fraction of light bulbs that are working is option D: number of light bulbs that are working/total number of light bulbs.
In this case, there are a total of 10 light bulbs, and 6 of them are not working. So the number of light bulbs that are working would be 10 - 6 = 4. Therefore, the fraction of light bulbs that are working is 4/10.