When a planetary system forms, the chances that a planet capable of su

Here is my method.

Whenever you see the word argument think conclusion.

There are only 3 parts any argument.

1) Premise: This is something that is presented as fact. It may or may not be true in the real world but in the argument it is presented as though it is true and should be treated so.

ex. All dogs run faster than cats.

You may be able to find a cat that can run faster than a dog in the real world but for the sake of the argument this is a fact because it is presented as such. There are no words in the sentence that lead to ambiguity.

2) Assumption: This is something that is not directly stated in the passage but MUST be inferred in order to reach the conclusion.

ex. All girls over 5 ft tall are good at basketball, therefore Stacy is good at basketball.

The assumption is that Stacy is over 5 ft tall. Without that assumption the conclusion that Stacy is good at basketball makes no sense.

3) Conclusion: The conclusion is something that is stated in the the passage but is not presented as fact. It is the opinion derived from the facts. It is all a matter of wording.

ex. Therefore, all dogs are faster than cats.

This is similar to the first sentence but in this case it is not presented as fact. The word 'therefore' signals that this is something that is trying to be proven.

For example you would not say I have lived for 30 years, therefore I'm 30. If your 30 years old that is a fact and you present it as such. I am 30 years old. But if you don't know for sure how old you are you could say something like: "I have a picture showing that I was born in 1978 therefore I must be 30."

So the first thing I do is figure out what the question is asking me.

Knowing which one of the following would be most useful in evaluating the argument?

So whenever I see argument I think conclusion. The conclusion IS the argument. You don't argue facts, you argue your conclusion based on facts.

So we are looking for information that will be helpful in evaluating the conclusion.

So I break out the conclusion from the premises.

Premise: the chances that a planet capable of supporting life will be formed are high.

Premise: The chances that a large planet the size of Jupiter or Saturn will be formed, however, are low.

Premise: Without Jupiter and Saturn, whose gravitational forces have prevented Earth from being frequently struck by large comets, intelligent life would never have arisen on Earth.

Conclusion: Since planetary systems are unlikely to contain any large planets, the chances that intelligent life will emerge on a planet are, therefore, low.

So now it clearer what information I'm looking for. I'm looking for information that will help me evaluated if the CHANCES that intelligent life will emerge on a planet are low.

The only things that affect these chances are.

1) Chances of a planet capable of supporting life
2) Chances of a large planet to deflect large comets
3) Chances life could survive a large comet strike
4) Chances that there are comets capable striking the planet

1, 2, 3, are already given and stated as fact. The only chance that we don't already know is the chance that a comet will strike the planet.

That is given in D.