Correct Answer: B

Rationale: The correct answer is B, Skeletal muscle. Skeletal muscle is a type of voluntary muscle tissue, allowing conscious control over its movement. Unlike smooth and cardiac muscle, which are involuntary, skeletal muscle is under direct voluntary control. Cardiac muscle (choice A) is involuntary and found in the heart. Smooth muscle (choice C) is also involuntary and found in the walls of internal organs. While skeletal muscle is striated (contains stripes), choice D is not the best answer as it does not specifically address the voluntary nature of skeletal muscle.

Correct Answer: C

Rationale: The motor cortex is located in the frontal portion of the brain, specifically in the precentral gyrus of the frontal lobe. It plays a crucial role in planning, controlling, and executing voluntary movements. Choice A, 'Top, middle portion of the parietal lobe,' is incorrect because the motor cortex is not located in the parietal lobe but rather in the frontal lobe. Choice B, 'Back of the head,' is incorrect as it refers to the occipital lobe, not where the motor cortex is situated. Choice D, 'Around the auditory cortex,' is incorrect as the motor cortex is not located around the auditory cortex but in the frontal lobe, as mentioned earlier.

Correct Answer: C

Rationale: The occipital lobe, located at the back of the brain, is primarily responsible for processing visual information received from the eyes. It plays a crucial role in interpreting and making sense of the visual stimuli perceived by the eyes, such as shapes, colors, and movement. This region is essential for visual perception and is specialized for processing and analyzing visual input, making it the correct answer. The frontal lobe is primarily involved in higher cognitive functions like decision-making and problem-solving, not visual processing. The parietal lobe is more related to sensory processes and spatial awareness, while the temporal lobe is primarily involved in processing auditory information and memory, not visual processing.

Correct Answer: A

Rationale: The correct answer is the pancreas. The pancreas is responsible for producing insulin, a hormone crucial for regulating blood glucose levels. Insulin plays a key role in allowing cells to take in glucose, thereby helping to keep blood sugar levels in check. The liver (choice B), gallbladder (choice C), and kidneys (choice D) do not produce insulin. The liver is involved in glycogen storage and glucose regulation, the gallbladder stores bile, and the kidneys filter blood and regulate fluid balance.

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. Choice B is incorrect because regulating body temperature is primarily the function of the body's thermoregulatory system, including sweat glands and blood vessels near the skin surface. Choice C is incorrect because while the cardiovascular system does help remove waste products through circulation, it is not its primary function. Choice D is incorrect as hormone production is mainly carried out by endocrine glands, not the cardiovascular system.