Correct Answer: B

Rationale: The correct answer is B because people of African descent commonly have a pigmented layer near the outer canthus of the lower lid called the "plica semilunaris." This is a normal anatomical variation in this population. Yellow fatty deposits over the cornea (choice A) are not typical findings in this demographic. Yellow color of the sclera extending up to the iris (choice C) is not a characteristic feature. The presence of small brown macules on the sclera (choice D) is also not a common finding in individuals of African descent.

Correct Answer: D

Rationale: The signs and symptoms - severe headache, high fever, and neck stiffness - in a young adult point towards meningeal inflammation. The combination of these symptoms is indicative of a potential infection or inflammation of the meninges, the protective membranes surrounding the brain and spinal cord. The presence of fever and neck stiffness, in addition to the severe headache, raises concern for meningitis, an infection of the meninges. This is a medical emergency that requires prompt evaluation and treatment. Other choices are incorrect because: A: Head injury usually presents with a history of trauma, which is not mentioned in the scenario. B: Cluster headaches typically do not present with fever and neck stiffness. C: Migraine headaches do not typically cause such high fever and neck stiffness.

Correct Answer: B

Rationale: The correct answer is B: hyphema. Hyphema is the presence of blood in the anterior chamber of the eye, which can occur due to trauma like being hit with a baseball bat. This indicates bleeding inside the eye, specifically in the space between the cornea and iris. Hypopyon (A) is the accumulation of white blood cells in the anterior chamber. Corneal abrasion (C) is a scratch on the cornea, not related to blood in the anterior chamber. Iritis (D) is inflammation of the iris, which does not necessarily involve blood in the anterior chamber.

Correct Answer: C

Rationale: The correct answer is C: Allergic rhinitis. The patient's symptoms of rhinorrhea, itching, and sneezing, along with pale, swollen turbinates and clear rhinorrhea, are indicative of allergic rhinitis. Allergic rhinitis is characterized by an allergic response to allergens, leading to inflammation of the nasal passages and increased mucus production. Nasal polyps (choice A) typically present with nasal congestion and reduced sense of smell. Acute sinusitis (choice B) would likely present with purulent nasal discharge and facial pain/pressure. Nasal carcinoma (choice D) is unlikely in this case due to the patient's symptoms and age.

Correct Answer: A

Rationale: The correct answer is A: At birth, the head is one fifth the total length. This is because newborns have relatively larger heads compared to their body size. This is known as cephalocaudal growth, where development starts from the head and progresses down the body. The head being one-fifth of the total length is a normal proportion in newborns. Choice B is incorrect because at birth, the chest circumference is usually greater than the head circumference. Choice C is incorrect as the head size reaches about 80% of its final size by age 2, not 3 years old. Choice D is incorrect because the closure of the anterior fontanelle at 2 months does not necessarily mean the head will appear proportionate to the body; it continues to grow in proportion to the body size.