One sunny afternoon, I went for a walk on the beach. There I saw a special crab (螃蟹). It had two claws (螯). One claw was much bigger and longer than the other. I had never seen such a crab before. So on my way home from the beach, I walked into the library.

    Luckily, I found a book named Come with Me. to the Edge of the Sea. It had many pictures of animals living near the sea. The pictures of male fiddler crabs (雄性招潮蟹) looked quite like the crab I found on the beach. I learned a lot about that kind of crab:

    Sometimes g fiddler crab puts the small Claw across big one. It looks like it is playing the fiddle (violin) when it does this so some people call it the fiddler crab Sometimes it waves (挥动) its big claw It looks like it is saying hello. That's why other people call it the calling crab Fiddler crabs eyes are on long eye stalks (眼柄). They can put up their eye stalks to look around. It makes them look taller.

    These crabs are very small. There are lots of other, bigger beach animals that want to eat them. They dig holes in the sand (在沙子里挖洞). The holes are their homes. They are safe inside them. Sometimes the sea water can bring food into their holes.

根据材料内容简要回答下列问题。

食物中能为人体各项生命活动提供能量的营养物质是（  ）