Correct Answer: B

Rationale: The main function of the large intestine is the absorption of water and electrolytes from indigestible food residues, helping to form solid waste (feces) for elimination. It mainly reabsorbs water and compacts the remaining material into feces, playing a crucial role in maintaining fluid balance in the body. Choices A, C, and D are incorrect because absorption of nutrients primarily occurs in the small intestine, secretion of digestive enzymes mainly occurs in the stomach and small intestine, and breaking down fats primarily occurs in the small intestine with the help of bile from the liver and enzymes.

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 nutrients. The small intestine's main role in the digestive system is to absorb nutrients from digested food. It has specialized structures, such as villi and microvilli, that increase its surface area for efficient absorption of nutrients into the bloodstream. Choice A is incorrect because the small intestine does not primarily secrete digestive enzymes; that role is mainly carried out by the pancreas and other digestive organs. Choice C is incorrect because the small intestine primarily absorbs nutrients rather than breaking down food. Choice D is incorrect because the absorption of water primarily occurs in the large intestine, not the small intestine.

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: B

Rationale: The correct answer is the Adrenal gland. The Adrenal glands, situated on top of the kidneys, are responsible for producing adrenaline. Adrenaline is a hormone that prepares the body for the fight-or-flight response during stress. Choice A, the Thyroid gland, is responsible for producing hormones that regulate metabolism, not adrenaline. Choice C, the Pituitary gland, regulates many of the body's functions by producing various hormones but is not responsible for adrenaline production. Choice D, the Pineal gland, produces melatonin, a hormone that regulates sleep-wake cycles, and is not responsible for adrenaline production.