In finance, the market efficiency establishes that market prices should not allow for the possibility of riskless profit or arbitrage in the absence of transaction costs. Which of the following sentences do NOT represent a clear situation of arbitrage with derivatives?

• a) Two assets with identical future cash flows trade at different prices.

• b) An asset does not trade at the present value of its future expected cash flows.

• c) An asset does not trade at the future value of its future expected cash flows.