In Which of the Following Cases Would a Fiduciary Duty

In which of the following cases would a fiduciary duty be breached?

A) A stockbroker advises a client to buy shares in a company in which he is a substantial shareholder without disclosing the fact of his preexisting shareholding to the client
B) A director of a company buys property from the company after misrepresenting its true value to the other members of the board of directors
C) A real estate agent who has been authorized to search for property buys a property and sells it back to his client for three times the value
D) A stockbroker advising an elderly woman on investing money after her husband died and she has no investing experience and he has her put it into a new startup he owns
E) All of the above