Answer:

Step-by-step explanation:
Let's analyze the answer choices. Remember we are looking for an unsustainable option.
A. Renewable energy is a great sustainable practice because it doesn't produce waste.
B. Using grocery bags once is not sustainable. Single use plastic is not good for the environment because it is used one time and then thrown out.
C. Energy efficient appliances are sustainable. They don't consume as much energy.
D. Recycling is always an environmentally friendly option. It allows some materials to be used again.
The choice that is not sustainable is B. using grocery bags only once before disposing of them.