In basic astronomy, according to increasing distance of the inner planets from the Sun, which of the following sequences of Mercury, Venus, Earth and Mars is correct from nearest to farthest from the Sun?

Introduction / Context:
The layout of the planets in our solar system is a fundamental topic in basic astronomy and general science. Knowing the correct order of the inner rocky planets from the Sun helps learners understand many other ideas, such as temperature differences, orbital periods and observational patterns in the sky. This question focuses specifically on the correct sequence of Mercury, Venus, Earth and Mars from nearest to farthest from the Sun.

Given Data / Assumptions:

• We are only considering four inner planets: Mercury, Venus, Earth and Mars.
• The ordering is based on average distance from the Sun along their nearly elliptical orbits.
• Distances are measured radially outward from the Sun, not by orbital period or size.
• We use the widely accepted modern model of the solar system where Mercury is the innermost planet.

Concept / Approach:
In the modern heliocentric model, planets orbit the Sun in order of increasing distance. The inner planets, also known as terrestrial planets, are Mercury, Venus, Earth and Mars. Mercury is closest to the Sun, followed by Venus, then Earth, and then Mars. This sequence is fixed and is independent of where the planets happen to be along their orbits at any particular moment in time. By comparing each of the given options with this well known order, we can identify the correct sequence easily and reject those that place Venus or Earth in the wrong relative positions.

Step-by-Step Solution:
Step 1: Recall the standard order of planets from the Sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus and Neptune. Step 2: Focus only on the four inner planets mentioned in the question: Mercury, Venus, Earth and Mars. Step 3: Note that among these, Mercury is the nearest to the Sun, followed by Venus, then Earth, and then Mars as the outermost of the four. Step 4: Check option a, which lists Mercury, Venus, Earth, Mars. This matches the known order. Step 5: Check options b, c and d and see that each places either Earth or Venus in the wrong position relative to the others, so they must be rejected.

Verification / Alternative check:
Standard astronomy charts and textbooks consistently show the distances of the inner planets from the Sun, often measured in astronomical units. These diagrams clearly list Mercury as the first planet, Venus as the second, Earth as the third and Mars as the fourth, in that exact sequence. Even simple memory aids used in classrooms follow this same order. Therefore, cross checking with authoritative sources confirms that the correct order is Mercury, Venus, Earth and Mars, which matches option a exactly.

Why Other Options Are Wrong:
Option b places Earth immediately after Mercury and pushes Venus outward, which contradicts the fact that Venus orbits between Mercury and Earth.

Option c incorrectly places Mars before Earth and Venus, even though Mars is farther from the Sun than both Earth and Venus.

Option d puts Mars directly after Mercury and moves Venus and Earth farther out, which does not match any accepted model of the solar system.

Common Pitfalls:
A common mistake is mixing up the order of Venus and Earth because they are both relatively close to the Sun and similar in size. Learners may also confuse orbital period with distance, assuming that a planet with a shorter year must always be closer, without remembering the established list. Using a simple mnemonic for the full sequence of planets and repeatedly visualising their orbits helps prevent such confusion and makes the correct order easy to recall in exams.

Final Answer:
The correct order of the planets from the Sun among the given sequences is Mercury, Venus, Earth, Mars.