Correct Answer: C

Rationale: The main function of the lymphatic system is to fight infections. It achieves this by filtering lymph, returning excess tissue fluid to the bloodstream, and aiding in the body's immune response. The lymphatic system is crucial in protecting the body against pathogens and maintaining overall health. Choices A, B, and D are incorrect because transporting oxygen, producing hormones, and transporting nutrients are functions performed by other systems in the body, like the respiratory, endocrine, and circulatory systems, respectively.

Correct Answer: B

Rationale: The correct answer is B: To absorb water. The primary role of the large intestine is to absorb water from indigestible food matter. This absorption process helps in forming solid waste for excretion. Nutrient absorption primarily occurs in the small intestine, not the large intestine. Breaking down food and secreting digestive enzymes are functions primarily associated with the stomach and small intestine.

Correct Answer: A

Rationale: The correct answer is A: To control breathing and heart rate. The medulla oblongata is a vital part of the brainstem responsible for regulating essential functions such as breathing, heart rate, and blood pressure. These functions are crucial for maintaining life, and the medulla oblongata plays a key role in ensuring the body's survival. Choices B, C, and D are incorrect because regulating body temperature is primarily controlled by the hypothalamus, coordinating voluntary movements is associated with the cerebellum and motor cortex, and processing sensory information is related to the thalamus and sensory cortex, not the medulla oblongata.

Correct Answer: B

Rationale: B-lymphocytes are produced in the red bone marrow. The red bone marrow is the primary site for B-cell development, where they mature before entering the circulation. The thymus is responsible for T-lymphocyte maturation, not B-lymphocytes. Lymph nodes and spleen play roles in immune responses but are not the primary sites for B-lymphocyte production.

Correct Answer: B

Rationale: The correct answer is B: Triceps brachii. The triceps brachii muscle is responsible for extending the elbow joint. It is located on the back of the upper arm and acts in opposition to the biceps brachii, which is responsible for elbow flexion. The deltoid muscle is primarily responsible for shoulder abduction, not elbow extension. The pectoralis major muscle is involved in movements of the shoulder joint, not the elbow.