Correct Answer: A

Rationale: The correct answer is A: 'To produce bile.' The liver's primary role in the digestive system is to produce bile. Bile is essential for emulsifying fats, aiding in their digestion and absorption in the small intestine. Choice B is incorrect because while the liver does secrete some digestive enzymes, its primary function is bile production. Choice C is incorrect because while the liver does store glucose, it is not its primary function in the digestive system. Choice D is incorrect because the liver produces bile, but it does not store it.

Correct Answer: B

Rationale: Neuroglia are specialized connective tissue cells that provide support and protection to neurons in the nervous system. They assist in the proper functioning of neurons and are essential for maintaining the overall health of nerve tissue. Therefore, in the context of nerve tissue composition, neuroglia are the connective tissue cells associated with neurons. The other choices, osteoblasts, osteocytes, and arterioles, are not the correct types of connective tissue cells found in nerve tissue. Osteoblasts are involved in bone formation, osteocytes are mature bone cells, and arterioles are small blood vessels that supply blood to tissues.

Correct Answer: A

Rationale: The correct answer is A: Protecting the body from external damage. The primary function of the integumentary system, which includes the skin, hair, and nails, is to act as a physical barrier that protects the body from external damage such as pathogens, UV radiation, and mechanical injuries. While the integumentary system does play roles in regulating body temperature and producing vitamin D, its main and most crucial function is to provide a protective shield for the body. Choices B, C, and D are incorrect because although the integumentary system contributes to regulating body temperature and producing vitamin D, as well as housing cells involved in the immune response, its primary role is protection.

Correct Answer: B

Rationale: The primary function of the digestive system is to break down food into smaller molecules and absorb nutrients such as vitamins, minerals, carbohydrates, proteins, and fats. These nutrients are then utilized by the body for energy, growth, and repair. The digestive system plays a crucial role in the process of extracting essential components from food and distributing them to the body's cells through the bloodstream. Choices A, C, and D are incorrect because transporting oxygen, producing hormones, and transporting blood are functions associated with other body systems like the respiratory system, endocrine system, and circulatory system, respectively, not the digestive system.

Correct Answer: A

Rationale: The correct answer is A: "To transport oxygen and nutrients." The primary function of the cardiovascular system is to transport oxygen, nutrients, and hormones to cells throughout the body and remove waste products. This system plays a crucial role in maintaining homeostasis by delivering essential substances to tissues and organs while eliminating metabolic waste. Choices B, C, and D are incorrect because although the cardiovascular system indirectly helps in removing waste products through circulation, its primary function is focused on transporting essential substances and not on regulating body temperature or fighting infections.