Correct Answer: B

Rationale: Cohort studies are types of epidemiological studies that involve a group of individuals who share a common characteristic or experience and are followed over time to observe the development of a particular health outcome. This type of study is useful in determining the incidence of a disease, identifying risk factors, and studying the natural history of a disease. Cohort studies allow researchers to investigate the relationship between exposure and outcome by following participants forward in time. It helps in establishing causality and is particularly useful for studying rare exposures or outcomes. In contrast, cross-sectional studies involve collecting data from a population at a single point in time, experimental studies involve interventions and control groups, and case-control studies involve comparing individuals with a particular health outcome (cases) to those without the outcome (controls) retrospectively.

Correct Answer: B

Rationale: Periodontitis is the dental condition characterized by inflammation of the gingival tissues surrounding the teeth. It is typically caused by poor oral hygiene practices, leading to plaque buildup and eventually gum disease. If left untreated, periodontitis can cause serious damage to the gum tissue and the underlying bones supporting the teeth, which can eventually result in tooth loss. Regular dental check-ups, proper oral hygiene habits, and professional cleanings are important for preventing and managing periodontitis.

Correct Answer: C

Rationale: Patients prescribed proton pump inhibitors (PPIs) for gastroesophageal reflux disease (GERD) should be instructed to take the medication 30 minutes before meals. This is because PPIs work best when taken on an empty stomach, allowing them to inhibit the gastric proton pump effectively and reduce acid production in anticipation of food intake. Taking the medication before meals ensures optimal absorption and effectiveness in controlling symptoms of GERD.

Correct Answer: D

Rationale: The presentation of a small, painless, well-defined nodule on the lateral aspect of the neck, above the clavicle, along with the cytology showing clusters of polygonal cells with abundant granular cytoplasm is most indicative of a parathyroid adenoma. Parathyroid adenomas are benign tumors derived from the parathyroid gland that can produce excess parathyroid hormone (PTH), leading to hyperparathyroidism. The characteristic histology of parathyroid adenomas includes chief cells with abundant granular cytoplasm.

Correct Answer: C

Rationale: The patient is presenting with sudden onset weakness and numbness on one side of the body, along with difficulty speaking and understanding speech, which are typical symptoms of a stroke. Imaging revealing an acute infarction involving the left middle cerebral artery territory is consistent with an ischemic stroke. Ischemic stroke occurs when there is a blockage in a blood vessel supplying blood to the brain, leading to a lack of oxygen and nutrients to the affected area, resulting in neurological deficits. This is in contrast to an intracerebral hemorrhage, which is caused by bleeding into the brain tissue, or a subarachnoid hemorrhage, which involves bleeding into the space surrounding the brain. A transient ischemic attack (TIA) is a temporary episode of neurological dysfunction caused by a brief blockage of blood flow to a part of the brain, usually resolving within 24 hours. In this case, the presentation and imaging findings are most