Answer:
Jupiter is the largest planet in our solar system. It is the fifth planet from the Sun and is known for its immense size and mass. Here are the reasons why Jupiter is the biggest planet among the options given:

1. Size and Diameter:
Jupiter has a diameter of about 143,000 kilometers, making it more than 11 times wider than Earth. In fact, it is so large that over 1,300 Earths could fit inside it. This makes Jupiter significantly larger than any other planet, including Saturn, which is known for its impressive size as well.

2. Mass:
Jupiter's mass is also the greatest among the planets in our solar system. It has a mass of approximately 1.898 × 10^27 kilograms, which is more than twice the mass of all the other planets combined. This immense mass contributes to Jupiter's gravitational pull and its ability to attract and capture other celestial objects.

3. Composition:
Jupiter is primarily composed of hydrogen and helium, which account for its massive size. Its atmosphere is mostly made up of hydrogen, while its core is believed to be a combination of heavier elements such as rock and metallic hydrogen. The presence of these elements contributes to the planet's large size and mass.

4. Great Red Spot:
One of the most iconic features of Jupiter is the Great Red Spot, a massive storm that has been raging for centuries. This storm is so large that it could engulf multiple Earth-sized planets. The presence of such a gigantic storm further emphasizes Jupiter's immense size.

5. Moons:
Jupiter has the largest number of moons in our solar system, with over 80 confirmed moons. Some of these moons, such as Ganymede, Callisto, and Io, are even larger than the planet Mercury. The presence of numerous large moons is another indication of Jupiter's significant size.

In conclusion, Jupiter is the largest planet in our solar system due to its immense size, diameter, mass, composition, and the presence of features like the Great Red Spot and numerous large moons.