问题如下图：
选项：
A. 
B. 
C. 
解释：是不是只有在弱式有效市场，active trading strategies要优于passive strategies？而半强式有效市场和强式有效市场passivestrategies是不是优于active ？
NO.PZ2015122802000084问题如下 If markets are semi-strong-form efficient, then passive portfolio management strategies are most likely to:A.earn abnormreturns.B.outperform active trang strategies.C.unrperform active trang strategies. is correct.Costs associatewith active trang strategies woulfficult to recover; thus, suactive trang strategies woulhave fficulty outperforming passive strategies on a consistent after-cost basis.考点Efficient CapitMarket AnIts Forms在半强有效市场中，active的策略也无法获得超额收益，但它比passive投资策略成本还高。所以passive投资策略会优于active投资策略。 为什么题目没说不允许内幕交易，却不能选C？所以就默认不能内幕交易了么？也就是说不会有强无效市场了么？
NO.PZ2015122802000084问题如下If markets are semi-strong-form efficient, then passive portfolio management strategies are most likely to:A.earn abnormreturns.B.outperform active trang strategies.C.unrperform active trang strategies. is correct.Costs associatewith active trang strategies woulfficult to recover; thus, suactive trang strategies woulhave fficulty outperforming passive strategies on a consistent after-cost basis.考点Efficient CapitMarket AnIts Forms在半强有效市场中，active的策略也无法获得超额收益，但它比passive投资策略成本还高。所以passive投资策略会优于active投资策略。 我以为是主动和被动结果是一样的，但为什么被动还能比主动好？
NO.PZ2015122802000084 问题如下 If markets are semi-strong-form efficient, then passive portfolio management strategies are most likely to: A.earn abnormreturns. B.outperform active trang strategies. C.unrperform active trang strategies. is correct.Costs associatewith active trang strategies woulfficult to recover; thus, suactive trang strategies woulhave fficulty outperforming passive strategies on a consistent after-cost basis.考点Efficient CapitMarket AnIts Forms在半强有效市场中，active的策略也无法获得超额收益，但它比passive投资策略成本还高。所以passive投资策略会优于active投资策略。 如题
NO.PZ2015122802000084 outperform active trang strategies. unrperform active trang strategies. B is correct. Costs associatewith active trang strategies woulfficult to recover; thus, suactive trang strategies woulhave fficulty outperforming passive strategies on a consistent after-cost basis. 考点Efficient CapitMarket AnIts Forms 在半强有效市场中，active的策略也无法获得超额收益，但它比passive投资策略成本还高。所以passive投资策略会优于active投资策略。 如题。。。。。。。。。
outperform active trang strategies. unrperform active trang strategies. B is correct. Costs associatewith active trang strategies woulfficult to recover; thus, suactive trang strategies woulhave fficulty outperforming passive strategies on a consistent after-cost basis.请问这道题A为什么不对？
