The following are multiple choice questions (with answers) about medical knowledge.   **Question:** Magnesium deficiency has been reported as an etiological cause for:   (A) Bruxism.   (B) Nail biting.   (C) Thumb sucking.   (D) All of the above.
['(A) Bruxism. <> answer', 'The following are multiple choice questions (with answers) about medical knowledge. <> instruction', '(A) Bruxism. \n (B) Nail biting. \n (C) Thumb sucking. \n (D) All of the above. <> possible answers', '  Magnesium deficiency has been reported as an etiological cause for: <> context@']