The device’s maker predicts that ranchers will buy the device at its current price, so any future price decrease is irrelevant. Thus, (A) doesn't provide a benefit of the device that outweighs or reduces its overall cost to explain why ranchers will purchase it at this price.

This highlights a key benefit of the device that reduces its overall cost and explains why ranchers will purchase it at the current price. The benefit is simply that ranchers only need to outfit a few leading cattle with the device, rather than outfitting the entire herd.

This does provide a benefit of the device, but not one that outweighs or reduces the overall cost of using it on a herd of cattle. Presumably there are other, cheaper means of keeping cattle in their pasture that also don’t cause stress. So what’s the benefit of this device?

If the device is as effective as fences, but fences are far less expensive, why will ranchers still purchase the device? We need a benefit of this device that outweighs or reduces its overall cost and causes ranchers to purchase it.

Like (A), the device’s maker predicts that ranchers will buy the device at its current price, so whether it is discounted for bulk purchases is not relevant. Thus, (E) doesn’t provide a benefit of the device that supports the device maker’s prediction.