Choose the sentence in this excerpt that indicates why airlines would be interested in the production of the jatropha plant.
They’re also testing a weedy African plant called jatropha. It’s no good to eat, and grows easily in dry, bad soil. But its seeds are filled with oil that could be a great–and cheap!–fuel. Airlines have already begun test-flying planes fueled partly with jatropha oil. With the help of the MRI machine, scientists hope to find the best, most oil-rich varieties for farmers to plant.