Online Testing, also known as Computer Assisted Assessment (CAA), is a sector of e-learning aimed at assessing learner’s knowledge through e-learning means. In recent years, the means for knowledge evaluation have evolved in order to satisfy the necessity of evaluating a big mass of learners in strict times: objective tests, more rapidly assessable, have gained a heavier weight in the determination of learners’ results. Multiple Choice question type is extremely popular in objective tests, since, among other advantages, a large number of tests based on it can be easily corrected automatically. These items are composed of a stem and a list of options. The stem is the text that states the question. The only correct answer is called the key, whilst the incorrect answers are called distractors (Woodford & Bancroft, 2005).