The United Bank of Glassen Lent Money to Only a Limited

The United Bank of Glassen lent money to only a limited number of big business houses. After a financial crisis, the bank went out of business. Which of the following reasons could have contributed to the collapse of this bank?

A) their decision not to lend funds to the Federal Reserve
B) their decision not to diversify their asset portfolio
C) their decision to extend loans to a diversified pool of borrowers
D) their decision to extend mainly short-term loans
E) their decision to unnecessarily scrutinize each borrower's details