Final answer:
Planet A, with its very dense atmosphere of carbon dioxide and a distance of 0.72 AU from the Sun, is Venus, while Planet B resembles Saturn with its rings and many moons.
Step-by-step explanation:
Based on the information provided, Planet A has a very dense atmosphere that is 96.5% carbon dioxide and 3.5% nitrogen, no moons, no rings, and a distance from the Sun of 0.72 AU (Astronomical Units).
Among the planets in our solar system, Venus is the one that closely matches this description. It has a thick atmosphere dominated by carbon dioxide, no natural satellites, and is the second planet from the Sun, orbiting at an average distance of about 0.72 AU.
In contrast, the second planet mentioned, Planet B, with 62 moons, visible rings, and a composition of hydrogen and helium, seems to resemble Saturn, which is known for its rings and numerous moons, and is located much further from the Sun at a distance of 9.54 AU.