Which of the following statements is true about arbitrage trades? Select one: A. In equilibrium, arbitrage trades cannot exist. B. In equilibrium, arbitrage trades can still exist. C. A trade (or set of trades) with a certain (probability one) positive return is an arbitrage trade. D. A trade (or set of trades) with a certain (probability one) negative return is an arbitrage trade. E. A trade (or set of trades) with a possible positive return is an arbitrage trade