Hopefully this explanation of what the different choices mean will be helpful: 1. She always brings recycling / recyclable bottles. Recyclable bottles means bottles that they are able to be recycled. Recycling bottles would mean bottles that are used for the purpose of recycling. 2. He likes the usable / user - friendly feautres of his new dishwater. Usable features would be a strange thing to say, since all features are usually able to be used. User-friendly means the features are easy to use, or friendly to the user of the dishwasher. 3. We have energy- efficency / energy- efficient lights in our house. Efficiency is a noun that refers to the idea of being efficient and doesn't quite fit here. Efficient is an adjective that describes the light, so it makes sense. 4. I only use natural- friendly / nature - friendly detergents. The detergents are friendly to nature (nature-friendly). You can't be friendly to "natural" because natural is not a thing, it is a description. 5. Disposing / Disposable batteries are bad for the environment. The batteries are able to be disposed (disposable). Disposing batteries would be batteries that are used for the purpose of disposing. But the purpose of batteries is not to dispose them, that's just something that you can do with them after they've been used.

Yes, this would be a difficult exercise for a learner! To answer it requires that the learner have much experience with common English usage. The WRONG adjectives would be: 1. recycling 2. usable 3. energy-efficiency 4. natural-friendly 5. Disposing

"But I got stuck in this exercise."