In terms of size among the eight major planets of the Solar System, what rank does the planet Jupiter hold?

Introduction / Context:
Planetary science often focuses on comparing the sizes and characteristics of planets within the Solar System. Knowing which planet is the largest helps build a mental picture of the structure of the system. Jupiter is widely known as a gas giant, and this question tests whether you can correctly state its size rank among the eight major planets orbiting the Sun.

Given Data / Assumptions:

- The set considered is the eight major planets, from Mercury to Neptune.
- The parameter for ranking is size, usually measured by diameter or volume.
- Options provide ranks from 1 to 4.
- We assume standard modern classification in which Jupiter and Saturn are gas giants and other planets are smaller.

Concept / Approach:
Among the eight planets, Jupiter is the largest in both mass and volume. It is significantly bigger than Saturn, which is the second largest planet. The terrestrial planets like Earth, Venus, Mars and Mercury are much smaller, and the ice giants Uranus and Neptune are also smaller than Jupiter. Therefore, when ranking planets by size from largest to smallest, Jupiter holds the first position.

Step-by-Step Solution:
Step 1: Recall the names of the eight planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune.Step 2: Identify Jupiter as one of the gas giants and visually much larger in diagrams than any other planet.Step 3: Recognise that Saturn is the second largest, followed by Uranus and Neptune among the outer planets.Step 4: Compare Jupiter with all others and note that it is the largest in terms of diameter and volume.Step 5: Conclude that in terms of size rank, Jupiter is number 1.

Verification / Alternative check:
Most school atlases and science textbooks contain comparative diagrams of planet sizes. These visuals clearly show Jupiter as the largest circle, with Saturn as the next largest. If you recall any such diagram, it becomes obvious that Jupiter tops the list. Another way is to remember basic facts like Jupiter could contain many Earth sized spheres inside it, emphasising its status as the largest planet in the Solar System.

Why Other Options Are Wrong:
Rank 2: This would correspond to Saturn, not Jupiter. So choosing 2 would confuse Jupiter with the second largest planet.
Rank 3: This might be associated with Uranus or Neptune depending on the parameter, but it is not correct for Jupiter.
Rank 4: This rank would belong to an even smaller planet, so it cannot be correct for Jupiter, which is clearly the most massive and largest in volume.

Common Pitfalls:
Some learners misremember the relative sizes of Saturn, Uranus and Neptune, but there is rarely confusion about Jupiter being the largest. Occasionally, people who have not seen scale diagrams may underestimate how much bigger Jupiter is than Earth or Saturn. Reviewing one or two standard diagrams of the planets by size is enough to fix this concept clearly and avoid errors in questions like this one.

Final Answer:
In terms of size, Jupiter ranks number 1 among the planets of the Solar System.