What is the correct method for answering exam questions?

The method of completely blackening the circle marked with the correct answer is designed to ensure clarity and precision in the marking process. This method is effective because it allows for easy reading by optical scanning machines, which are often used to grade standardized exams. The darkened bubble signals that this option is the selected answer, thereby minimizing the chances of misinterpretation or errors during grading.

In contrast, lightly ticking the answer or writing in the margins can lead to ambiguity. Highlighting options may not be recognized properly by scanning systems or may result in the answer not being counted at all, ultimately affecting the accuracy of the exam results. Thus, using the completely blackened circle ensures the response is clear and adheres to the required standards for exam-taking.