问题如下：
Arbitrage opportunities exist when:
选项：
A.two identical assets or derivatives sell for different prices.
B.combinations of the underlying asset and a derivative earn the risk-free rate.
C.arbitrageurs simultaneously buy takeover targets and sell takeover acquirers.
解释：
A is correct.
Arbitrage opportunities exist when the same asset or two equivalent combinations of assets that produce the same results sell for different prices. When this situation occurs, market participants would buy the asset in the cheaper market and simultaneously sell it in the more expensive market, thus earning a riskless arbitrage profit without committing any capital.
B is incorrect because it is not the definition of an arbitrage opportunity. C is incorrect because it is not the definition of an arbitrage opportunity.
想问一下课件中Arbitrage has no effect of equalizing risk among market participants.这句话是什么意思呢？如何理解，谢谢！
