In this simple riddle, what has teeth but cannot bite?

Introduction / Context:
This question presents a classic one line riddle: What has teeth but cannot bite? Instead of referring to the teeth in a mouth, the riddle plays on the word teeth as used in everyday objects. The goal is to identify a common household item whose parts are called teeth, even though it does not actually bite in the way an animal does.

Given Data / Assumptions:
• The riddle is What has teeth but cannot bite?
• The options are comb, saw, zipper and gear.
• We assume the riddle is aimed at simple, common objects that even children recognise.
• We also assume the focus is on a single most popular traditional answer rather than all possible technical uses of the word teeth.

Concept / Approach:
In everyday language, the part of a comb that separates hair consists of small pointed pieces that are commonly called teeth. A comb is often used in examples when explaining this riddle to young learners. The comb clearly has teeth, but it cannot bite like an animal. Saws, zippers and gears also have parts called teeth in technical usage, but in general riddle tradition, the simplest and most widely accepted answer is comb. Therefore, the correct choice in this context is comb.

Step-by-Step Solution:
Step 1: Think of household objects described as having teeth in ordinary speech, not just in engineering terminology. Step 2: Recall that hair combs have many narrow prongs known as teeth, which are designed to pass through hair. Step 3: Note that a comb, despite having teeth, does not bite, chew or eat anything in the sense that animals do. Step 4: Compare this with other options. While a saw and a gear may have teeth, these are more often mentioned in technical or mechanical contexts. Step 5: Conclude that comb is the standard riddle answer and matches the common teaching usage for this question.

Verification / Alternative check:
You can verify by thinking about how the riddle is usually presented to children. Teachers and puzzle books almost always give comb as the answer, because it is safe, familiar and visually clear. If you show a comb to someone and ask what these small pieces are called, many will automatically call them teeth. In contrast, if you show a zipper or a gear, not everyone spontaneously uses the word teeth unless they are told the technical term. This supports comb as the intended answer in a general knowledge puzzle.

Why Other Options Are Wrong:
• Saw: A saw is sometimes said to have teeth, but in many basic riddle collections, the comb example is preferred because it is harmless and used daily.
• Zipper: One can describe the parts of a zipper as teeth, but this is less traditional in simple riddles and might confuse younger learners.
• Gear: Gear teeth are common in mechanical engineering, but gears are not as familiar to all ages as combs are.

Common Pitfalls:
One pitfall is thinking too technically and arguing that there are many objects with teeth in the mechanical sense. Another is trying to find a clever but obscure answer instead of the conventional one. For exam style riddles, it is usually best to choose the simplest, most common answer that fits naturally. Here, remembering that comb teeth are a regular part of daily grooming makes the solution straightforward.

Final Answer:
The everyday object that has teeth but cannot bite, in the usual wording of this riddle, is a comb.