Final answer:
Enron was the company involved in energy and resource trading. Arthur Andersen was an accounting firm, while WorldCom and Adelphia were involved in different scandals. Lehman Brothers' bankruptcy in 2008 marked the onset of the global financial crisis.
Step-by-step explanation:
The company involved in energy and other resource trading mentioned in the question is Enron. Enron became infamous for its bankruptcy and the scandal that unfolded due to its fraudulent accounting practices. In contrast, Arthur Andersen was the accounting firm associated with the Enron scandal, WorldCom was involved in a major accounting scandal related to fraudulent financial reporting, and Adelphia was involved in a scandal due to committing corporate fraud.
Regarding the investment banking firm that went bankrupt in 2008 and signaled the beginning of a major economic crisis, the correct answer is Lehman Brothers. Its collapse was one of the most significant moments of the 2008 financial crisis.