ANSWER
D. The grocery store charges $1 less per lightbulb.
Step-by-step explanation
To find the cost per lightbulb we have to divide the total cost of each pack by the number of lightbulbs in each pack. For the hardware store,
![(20)/(4)=5](https://img.qammunity.org/2023/formulas/mathematics/college/l6sa8tf90w312mo48k586k5dohxvm16evc.png)
The cost per lightbulb is $5. And for the grocery store,
![(24)/(6)=4](https://img.qammunity.org/2023/formulas/mathematics/college/7ygi1n39ol3h7xs5p3ru5106fpzqf6up3d.png)
The cost per lightbulb is $4.
Hence, the grocery store charges $1 less per lightbulb than the hardware store.