We mark $20 bills larger with a _______ ___.

• A. Counterfeit Pen
• B. UV Marker
• C. Security Pen
• D. Insect Pen

Answer: (A)

The main idea is quickly confirming currency authenticity using a dedicated detection tool. A counterfeit detector pen is designed for this purpose: it marks the bill with a chemical that reacts with starch found in many counterfeit papers. Real U.S. currency, made from cotton-linen, has little starch, so the mark stays pale. If the mark darkens, it’s a red flag for counterfeit. UV features and other tools exist, but the standard on-the-spot quick check described here is with a counterfeit pen. Insect pen isn’t a real tool, and while a security pen could be confused with the counterfeit pen, the specific name and reaction are what make it the best choice. Always use multiple checks and follow policy.