A non-restrictive modifier add information that does not restrict who the subject can refer to (compare to "The one Marlena that enjoys many subjects" -this one restricts the subject to a specific Marlena). Here it's "who enjoys many different subjects" - it adds additional information about her, but doesn't change the referent.
Hello. You forgot to show the answer options. The options are:
Other industries became more successful and provided needed jobs.
Most successful business owners refused to assist those in need.
Americans realized that business was not immune to failure and could collapse.
Average Americans became the victims of unethical business owners.
Answer:
Americans realized that business was not immune to failure and could collapse.
Explanation:
With the stock market crash, Americans realized that business was not immune to problems, that they could not provide infinite stability to American citizens, as they were susceptible to unfortunate adversities that could cause a major imbalance at any time. They will understand that it was necessary to invest in diversified things and not to put all faith in a single economic branch, because the economy is something very unstable and delicate.
