Final answer:
The correct answer is D as the generator allows the backpacker to carry more items without the added weight of batteries since it generates the necessary energy to power devices. The correct answer is the backpacker can carry more things, but it will not increase the weight of the backpack.
Step-by-step explanation:
If adding the generator to a backpack means that a backpacker does not need to carry batteries, then the backpacker can carry more things, but it will not increase the weight of the backpack. This is because the generator would supposedly provide the energy needed to power devices traditionally powered by batteries, such as a flashlight or a cell phone. The generator itself would likely harness energy from the motion of the backpacker or from some renewable source like solar power. Hence, the devices like a cell phone or flashlight would not lose power, and there is no mention that the generator needs pre-charging, making options A, B, and C incorrect.