What is an item called on a test question that is false or incorrectly designed to be a "plausible alternative" to the correct answer?

The term for an item on a test question that is false or incorrectly designed to appear as a plausible alternative to the correct answer is referred to as a distracter. In the context of standardized testing and assessments, distracters are intentionally crafted to challenge the test-taker's knowledge and understanding of the subject matter. They serve the purpose of making the assessment more rigorous by requiring students not only to identify the correct answer but also to discern it from those that may seem reasonable or relevant at first glance. Effective distracters can enhance the validity of a test by ensuring that only those with a solid grasp of the material can select the correct response, thus providing a better measure of the test-taker's knowledge and skills.