A group of unusual meteorites was found in Shergotty, India. Their str

Hello nightblade354,

could you please help me to clarify difference between (A) and (B)?

Argument states: Some meteorites found in India ---> Most probably originated: Mercury, Venus, or Mars.
Meteorites cannot be originated on Mercury ---> because of close proximity with Sun
Meteorites cannot be originated on Venus ---> because of its gravity
So only one possible answer that meteorites originate on Mars.

In my opinion (A) is correct, I don't know this is because of my poor english or some concept gaps.
The author presents counterexamples to the theory that Meteorites originated on Mercury, Venus, or Mars. So we only can infer that they originated on Mars.
How we consider this examples as alternative explanations?

To me alternative explanation will be in this case --->
Original: Meteorites originated on Mercury, Venus, or Mars.
Alternative: Meteorites' structure indicates that the origin could be Jupiter.

Or this is 'rule' that when we face this kind of argument structure it will be considered as alternative explanation rather than as counterexample?

A group of unusual meteorites was found in Shergotty, India. Their structure indicates that they originated on one of the geologically active planets: Mercury, Venus, or Mars. Because of Mercury’s proximity to the Sun, any material dislodged from that planet’s surface would have been captured by the Sun, rather than falling to Earth as meteorites, nor could Venus be the source of the meteorites, because its gravity would have prevented dislodged material from escaping into space. The meteorites, therefore, probably fell to Earth after being dislodged from Mars, perhaps as the result of a collision with a large object.

Context: A group of unusual meteorites was found in Shergotty, India. Their structure indicates that they originated on one of the geologically active planets: Mercury, Venus, or Mars

P: Because of Mercury’s proximity to the Sun, any material dislodged from that planet’s surface would have been captured by the Sun, rather than falling to Earth as meteorites

P: nor could Venus be the source of the meteorites, because its gravity would have prevented dislodged material from escaping into space

C: The meteorites, therefore, probably fell to Earth after being dislodged from Mars, perhaps as the result of a collision with a large object

OK, so you have items that are falling to Earth from three possible planets. We are told that it is not Mercury because it is too close to the sun, and we are told it is not Venus because its gravity is too strong. So what does the conclusion do? It states our third option, after eliminating the other two possibilities. Let's see if we can find that answer below.

The argument derives its conclusion by:

(A) offering a counterexample to a theory -- No counterexamples given. This would be similar to saying "All these materials actually come from Earth, so we have no reason to look towards space" or "But, items from Venus have actually been found on Earth". It would be something out of the blue that attacks our old argument in some way. This does not do that. Out.

(B) eliminating competing alternative explanations -- Perfect. We eliminated two of our three hypotheses and drew our conclusion off of the third one.

(C) contrasting present circumstances with past circumstances -- This would be like saying "well, 50 million years ago this happened, so therefore this occurred." Out.

(D) questioning an assumption -- Nope, once more we are restating the facts of our hypothesis after eliminating others. If we had said "oh, wait. But there is a fourth planet, and because of X, the meteorites could be coming from there", we would be questioning the assumption that there are only three other plants where this could come from. Out.

(E) abstracting a general principle from specific data -- A general principle is not given. We are told a specific case and three outcomes. Nothing general. If our argument talked about the three planets, but then said "therefore, all objects falling to Earth are from Mars" or "Therefore, all objects falling to a planet come from one close", we would be getting abstract from general. Out.

nightblade354 thank you for your time and detailed explanation.
Seems my mistake is lack of understanding the terms of 'counterexample' and 'alternative source' itself.

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