Correct Answer: B

Rationale: The correct answer is B: Thyroid gland. The thyroid gland is responsible for regulating the body's metabolism by producing hormones like thyroxine. These hormones play a key role in controlling the body's metabolic rate and energy production. Choice A, the pituitary gland, is often referred to as the 'master gland' but is not primarily responsible for regulating metabolism. Choice C, the adrenal gland, is involved in producing hormones like adrenaline and cortisol, which are crucial for the body's stress response but not primarily for metabolism. Choice D, the pineal gland, is responsible for producing melatonin, which regulates sleep-wake cycles and not directly related to metabolic regulation.

Correct Answer: B

Rationale: The correct answer is B: Kidneys. The kidneys are vital organs in the human body responsible for filtering blood to remove waste products and excess substances, producing urine as a result. The liver plays a role in detoxification and metabolism. The pancreas is involved in digestion and blood sugar regulation. The heart pumps blood throughout the body but does not filter blood or produce urine.

Correct Answer: B

Rationale: Responsiveness is the correct term that refers to the ability to detect and respond to changes in the internal and external environment. In this context, growth is incorrect as it pertains to an increase in size or number, reproduction involves producing offspring, and development refers to the process of growth, maturation, and differentiation of cells and tissues. Therefore, 'Responsiveness' is the most appropriate term for the given description.

Correct Answer: B

Rationale: Connective tissue is the correct answer as it provides support, structure, and strength to the body by holding tissues and organs in place. Muscle tissue is primarily responsible for movement, nervous tissue for communication, and epithelial tissue for covering and lining surfaces. While muscle tissue allows for voluntary and involuntary movement, nervous tissue transmits electrical signals, and epithelial tissue acts as a protective barrier and is involved in absorption and secretion. Therefore, in the context of providing support and structure, connective tissue is the most appropriate choice.

Correct Answer: C

Rationale: The correct answer is 'Sarcomere.' The sarcomere is the smallest repeating unit within myofibrils and is responsible for muscle contraction in skeletal muscle. It consists of overlapping actin and myosin filaments arranged in a highly organized structure that allows for the sliding of filaments during muscle contraction. 'Myofibril' (choice A) is incorrect because it is a larger structure composed of sarcomeres. 'Actin' (choice B) and 'Myosin' (choice D) are incorrect as they are individual proteins that are components of the sarcomere, not the smallest repeating unit itself.