问题如下：
Which of Martin’s statements relating to the introduction of electronic markets is correct?
选项：
A.Statement 1
Statement 2
Statement 3
解释：
A is correct. Once built, electronic systems are indeed cheaper to operate than floor-based trading systems. They require less physical space than do trading floors, and in contrast to floor-based trading systems, they do not require exchange officials to record and report prices. Furthermore, the widespread use of electronic trading systems significantly decreased trading costs for buy-side traders. Costs fell as exchanges obtained greater cost efficiencies from using electronic matching systems instead of floor-based manual trading systems.These technologies also decreased costs and increased efficiencies for the dealers and arbitrageurs who provide much of the liquidity offered at exchanges. Competition forced them to pass along much of the benefits of their new technologies to buy-side traders in the form of narrower spreads quoted for larger
sizes. New electronic buy-side order management systems also decreased buyside trading costs by allowing a smaller number of buy-side traders to process more orders and to process them more efficiently than manual traders. While electronic trading has had a significant effect on equity markets, it has not had as much of an effect on the markets for corporate and municipal bonds. The market structures of corporate and municipal bond markets have hardly changed since the late 19th century. Despite the efforts of many creative developers of electronic bond trading systems, most public investors in these markets still trade largely over the counter with dealers
老师， 所以traders 一般是指帮助机构进行购买或者卖是吧， 他们不赚差价是吧？ 但是dealers 赚的是spread 差价？
但是因为不需要trader下单，所以trader更少， 但是因为下单便捷，更多dealer进来买卖？
感觉一般大家说自己是trader感觉也是赚差价的职业，但是CFA不是这么定义的是么？
