Multiple choice items consist of a stem and a set of options. The stem is the beginning part of the item that presents the item as a problem to be solved, a question asked of the respondent, or an incomplete statement to be completed, as well as any other relevant information. The options are the possible answers that the examiner can choose from, with the correct answer called the key and the incorrect answers called distractors.[4] Only one answer can be keyed as correct. This contrasts with multiple response items in which more than one answer may be keyed as correct.
Usually, a correct answer earns a set number of points toward the total mark, and an incorrect answer earns nothing. However, tests may also award partial credit for unanswered questions or penalize students for incorrect answers, to discourage guessing. For example, the SAT removes a quarter point from the test taker's score for an incorrect answer.
For advanced items, such as an applied knowledge item, the stem can consist of multiple parts. The stem can include extended or ancillary material such as a vignette, a case study, a graph, a table, or a detailed description which has multiple elements to it. Anything may be included as long as it is necessary to ensure the utmost validity and authenticity to the item. The stem ends with a lead-in question explaining how the respondent must answer. In a medical multiple choice items, a lead-in question may ask "What is the most likely diagnosis?" or "What pathogen is the most likely cause?" in reference to a case study that was previously presented.
The items of a multiple choice test are often colloquially referred to as "questions," but this is a misnomer because many items are not phrased as questions. For example, they can be presented as incomplete statements, analogies, or mathematical equations. Thus, the more general term "item" is a more appropriate label. Items are stored in an item bank.