I have a problem for my English excercise

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There are two simple sentences 1. Land conservation is not the only advantage 2. The advantage is of a meatless diet. I am required to combine the two sentences with a subordinator to create a complex sentence. The key is "because " Land conservation is not the only advantage because the advantage is of a meatless diet. But how could I interpret the sentence above? why meatless diet? Many thanks to all