Why is this the answer?

The answer is inkstand because this riddle is a very clever word puzzle that plays a big trick with the letters K, S, and T. It wants you to think about where these three special letters are placed inside a single word. The key to solving this mystery is to find a word that has all three letters—K, S, and T—hidden inside it, right next to each other. If you look very closely at the word inkstand, you will see that all three of those letters are lined up right in the middle! The word is put together like this: I-N at the beginning, then K-S-T, and finally A-N-D at the very end. The main, solid piece of the word is K-S-T, which is why the riddle focuses on it. This makes the K-S-T part of inKSTand the center of the whole word. The riddle is a little sneaky because it asks for KST in the beginning, in the middle, and at the end. It does not mean the word must have KST written three times. Instead, it is a fun word game designed to trick your brain! The letters K, S, and T start the middle part of the word, they are the complete middle part, and they also end the middle part. This way, the KST is very important to the word's structure, acting as its core. An inkstand is a special little container that people used long ago to hold their bottles of ink and their pens on a desk. It was a very important place for writing. The letters K, S, and T are all together and form the core of the word, which is what makes inkstand the tricky and perfect answer to this word game. The riddle is all about seeing the letters inside the word, like a hidden picture that you have to find.