Correct Answer: B

Rationale: The correct answer is B: Ligaments. Ligaments are tough, flexible connective tissues that connect bones to other bones, providing stability and support to joints. Tendons (choice A) connect muscles to bones, enabling movement. Cartilage (choice C) is a firm, rubbery material that cushions bones at joints. Muscles (choice D) are contractile tissues responsible for movement. Therefore, when looking for the tissue that connects bones to other bones, ligaments are the most appropriate choice.

Correct Answer: C

Rationale: The main function of the adrenal glands is to produce hormones like adrenaline and cortisol. These hormones play a crucial role in regulating blood pressure, metabolism, and the body's stress response. While the adrenal glands do have some impact on metabolism, their primary function is not the direct regulation of metabolism. They are not involved in the production of bile or insulin. Therefore, the correct answer is the regulation of blood pressure.

Correct Answer: B

Rationale: The primary function of the immune system is to fight infections. It identifies and destroys pathogens like bacteria and viruses, protecting the body from harmful substances. While oxygen transportation is carried out by the respiratory system, energy production is mainly the role of the metabolic system, and body temperature regulation is managed by the thermoregulatory system. These functions are separate from the immune system's primary role of defending the body against infections.

Correct Answer: B

Rationale: The correct answer is B: 'To break down food.' The stomach plays a crucial role in the digestive system by breaking down food using gastric acid and digestive enzymes. This process transforms the food into a semi-liquid mixture known as chyme, which is further digested in the small intestine. Choices A, C, and D are incorrect because the stomach does not primarily absorb nutrients, produce bile, or store waste. These functions are carried out by other organs in the digestive system such as the small intestine, liver, and large intestine, respectively.

Correct Answer: B

Rationale: The primary function of the kidneys in the urinary system is to filter blood to remove waste products and excess fluids, which are then excreted as urine. Kidneys act as a filtration system, removing waste like urea, excess salts, and toxins. While the kidneys do play a role in regulating blood pressure by secreting renin and maintaining electrolyte balance by adjusting the levels of sodium, potassium, and other ions in the blood, their main and essential function is filtration and waste removal, making choice B the correct answer.