Kaplan Nursing Entrance Practice Exam 2025 – The All-in-One Guide to Exam Success!

Nuclear fusion in the sun primarily involves the combination of hydrogen nuclei, specifically the isotope of hydrogen known as protium (1H), to form helium (4He). This process occurs in several steps, with the most significant pathway being the proton-proton chain reaction. In this reaction, four hydrogen nuclei ultimately fuse to create one helium nucleus, releasing a substantial amount of energy in the form of light and heat, which is emitted by the sun. This energy is critical in providing warmth and light to our solar system.

The correct answer emphasizes the fundamental process that powers the sun and produces its energy, illustrating the transformation from light elements to a heavier element, helium, through fusion. This fusion is essential for sustaining the sun's life cycle and maintaining its luminosity over billions of years. Understanding this process is crucial in grasping how stars, including our sun, generate energy and influence their surroundings.