Concept:Problem-solving method uses systematic steps for independent or guided learning. A major drawback is that it is purely individualistic and does not encourage collaboration.Explanation:This method can become repetitive if overused. It may also lead to selection of trivial or outdated topics. However, the key demerit among the options is its individualistic nature, as it focuses on the student alone. It does not effectively bring emotional or attitudinal changes. While it builds cognitive skills, it does not inherently develop critical thinking if not structured properly. Thus, the main disadvantage is that it is purely individualistic.Answer:A. It is purely individualistic in nature.