Is "Are fruits a natural source of generating energy?" a problem statement?

The problem is sloppy thinking. Fruits are a natural source of sugar, vitamins, and minerals. Those things contribute to an intricate process called metabolism. That refers to the entire process from eating food to moving a muscle. Many/most people sloppily call that "energy". Energy is not a physical unit. It is a philosophical concept and an accounting technique used to analyze mechanical and chemical exchanges. In nuclear physics it is defined as a color of light, in biology it is a synonym for metabolism, and in public utilities they say energy when they mean connectivity. If the word is used in any other context, the speaker either doesn't know what he is talking about, or he is trying to peddle something you don't need.