Thanks for the question! The answer to this question is actually (B), and let me explain why. We’re told that universal acceptance of scientific theories that regard human beings only as natural objects subject to natural forces outside your control will lead to a decline in morality. This is the conclusion of the stimulus and can be diagrammed
Humans regarded only as natural objects —> Moral decline
Then we’re told that if people don’t believe they’re responsible for their actions, they will feel unashamed when acting immorally, which can be diagrammed as
~Believe responsible —> Unashamed when acting immorally
And then we’re told that people not feeling ashamed of immoral actions leads to general moral decline, in other words
Unashamed when acting immorally —> Moral decline
So we can see that we need something to connect the idea of “humans regarded only as natural objects” to “~Believe responsible,” since that’ll allow us to make the following chain
Humans regarded only as natural objects —> ~Believe responsible —> Unashamed when acting immorally —> Moral decline
Which simplifies to
Humans regarded only as natural objects —> Moral decline
And this is what (B) does, and so (B) makes the conclusion follow logically when assumed and is the correct answer.