Biologist: Scientists have discovered fossilized bacteria in rocks 3.5 billion years old. The fossils indicate that t...

on November 12, 2017

Answer choice C

Why is answer choice C the correct answer?

2 Replies

Mehran on November 12, 2017

Hi there, thanks for your post. This is an Argument Structure question. Let's start with an analysis of the argument in the stimulus:
P: Scientists have discovered fossilized bacteria in rocks 3.5 billion years old.
P: The fossils indicate that these bacteria were quite complex and so
SC: must have already had a long evolutionary history when fossilized 3.5 billion years ago.
P: However, Earth is only 4.6 billion years old, so
SC: the first life on Earth must have appeared soon after the planet's formation, when conditions were extremely harsh.
C: This suggests that life may be able to arise under many difficult conditions throughout the universe.

As you can see, the stimulus has a series of premises, including two subsidiary conclusions (SCs). A subsidiary conclusion is a statement that is supported by a premise, but which itself (in turn) acts as support for the ultimate conclusion.

That is why answer choice (C) is correct. Hope this helps!

on November 12, 2017

Thanks!