Why Did Goldman Sachs Have to Pay a Fine of Half

Why did Goldman Sachs have to pay a fine of half a billion dollars in 2010?

A) It had underwritten most of the subprime mortgages during the real estate boom.
B) It had failed to document its business structure to the Securities and Exchange Commission.
C) It had knowingly sold toxic mortgage-based securities and then bet on their failure.
D) It had illegally financed the presidential campaign of Barack Obama.
E) It had failed to reform its management and business practice in the wake of the mortgage crisis.