The spleen, a large lymphatic organ, is located in the:

Correct Answer: B

Rationale: The spleen is located in the abdomen, specifically in the upper left part of the abdomen, under the ribcage and above the stomach. It is an important organ in the lymphatic system responsible for filtering blood, storing blood cells, and fighting infection. It is not located in the chest, pelvis, or head and neck regions. Therefore, the correct answer is 'B: Abdomen.' Choices 'A: Chest,' 'C: Pelvis,' and 'D: Head and neck' are incorrect as the spleen is not situated in these anatomical areas.

Correct Answer: A

Rationale: The P wave on an electrocardiogram (ECG) represents atrial depolarization, which signifies the electrical activation of the atria as they prepare to contract. During the cardiac cycle, atrial depolarization occurs first, leading to atrial contraction. Ventricular depolarization is represented by the QRS complex, not the P wave. Choices B, C, and D are incorrect because the P wave specifically corresponds to atrial depolarization, not ventricular depolarization, atrial repolarization, or ventricular repolarization.

Correct Answer: D

Rationale: Dense irregular connective tissue, found in tendons and ligaments, provides tensile strength. Tendons and ligaments need to withstand tension and forces acting upon them, and the dense irregular connective tissue helps provide this strength and support. Choice A, flexibility, is incorrect because tendons and ligaments primarily provide support and stability rather than flexibility. Choice B, lubrication, is not the main function of dense irregular connective tissue in tendons and ligaments. Choice C, insulation, is also incorrect as this tissue type is not primarily involved in providing insulation.

Correct Answer: A

Rationale: The femur, also known as the thigh bone, holds the title of the largest bone in the human body. Situated in the upper leg, the femur plays a vital role in supporting the body's weight and enabling movement. While the tibia (shin bone), humerus (upper arm bone), and scapula (shoulder blade) are all essential bones, none of them match the femur in terms of size and importance. The tibia, humerus, and scapula are comparatively smaller bones with specific functions in their respective areas of the body, but they do not surpass the femur in size or significance.

Correct Answer: C

Rationale: To find the acceleration, we use the formula: acceleration = (final velocity - initial velocity) / time. Given that the final velocity is 0 m/s (as the object stops), the initial velocity is 20 m/s, and the time taken is 5 seconds. Substituting these values into the formula, we get acceleration = (0 m/s - 20 m/s) / 5 s = -20 m/s / 5 s = -4 m/s². Therefore, the acceleration is -4 m/s², indicating that the object decelerated at a rate of 4 m/s² to come to a complete stop. Choice A is incorrect because the object does experience acceleration as it changes its speed from 20 m/s to 0 m/s. Choice B is incorrect as it represents acceleration in the wrong direction, considering the object is decelerating. Choice D is incorrect as there is sufficient information provided to calculate the acceleration based on the given data.