Why is this the answer?

The answer is finger because this amazing riddle gives us three excellent clues that perfectly describe one of the most useful parts of your hand! It is a fun riddle that helps us look at something we see and use every day in a brand new, secret code kind of way. Let us look at the first clue: "Long and think." If you hold up your own hand and look at your fingers, you will see they are all long, slender shapes. They are designed this way so you can reach, point, and grip things. They are thin so they can fit into small spaces and pick up tiny objects like crumbs or beads. The word "think" might be a little trick, since you use your fingers to hold a pencil while you think, or you tap your fingers when you are thinking hard about a problem! This first part of the riddle is a perfect picture of the shape and function of this important body part. The next part of the riddle says, "red within." This is a clever clue, but it makes a lot of sense when you remember what is inside your body. Even though the outside of your skin might look light, underneath it all is your blood, which is red! If you press your finger gently, you can see the color change for a moment before it goes back to normal. The soft, living tissue that makes up the inside of your finger has that reddish color, proving that this tiny riddle knows all about human anatomy. It is a secret key that tells you it must be a part of a living creature. Finally, the last part of the riddle is the easiest clue to figure out: "with a nail at the end." This is the strongest piece of evidence! Every single one of your fingers, and your thumbs too, has a fingernail right on the tip. A fingernail is made of a tough material and acts like a tiny, hard shield to protect the soft tip of your finger. It is shaped like a tiny shell or a shield, and the riddle is using the word "nail" as a fun way to describe that little, hard bit at the very tip. When you put all these creative clues together, from the long shape to the reddish insides and the shield-like nail at the end, they all point directly to the answer: finger. This riddle is a smart way to celebrate the wonderful, complicated tools you carry with you all day long, doing all your important work and play!