The best answer is B.
This choice clearly and specifically defines why the speaker is both relieved and regretful. The other options are a bit vague and do not directly relate to the idea of learning to be responsible about money.
the tree branches reached out towards the windows with clawing fingers.
the moon was an eerie lantern in the night sky.
It's A. The subject is concern for the continued existence of the panther (the concern is what the sentence is about), and the phrase 'Because the panther is endangered already' comes before it.
