​Which of the following is(are) the characteristics of a bubble

A) ​Bubbles emerge when investors disagree about the particular economic importance of an event
B) Bubbles involve very large increases in trading volume
C) Bubbles may continue even when many expect a bubble and doesn't pop until a sufficient number of skeptical investors act simultaneously
D) ​All of the above

Katz reports total revenue of $245,600,cost of goods sold of $18,950 and net income of $121,000.Their total assets are $585,000 and total liabilities are $250,000.What is their return on equity (ROE) ?

A) 36.12%
B) 48.40%
C) 20.68%
D) 41.98%