问题如下：
After providing Hudgens with advice on direct investment, Soto offered him additional information on alternative indirect investment strategies using (1) bond mutual funds, (2) exchange-traded funds (ETFs), and (3) total return swaps. Hudgens expresses interest in using bond mutual funds rather than the other strategies for the following reasons.
Reason 1：Total return swaps have much higher transaction costs and initial cash outlay than bond mutual funds.
Reason 2：Unlike bond mutual funds, bond ETFs can trade at discounts to their underlying indexes, and those discounts can persist.
Reason 3：Bond mutual funds can be traded throughout the day at the net asset value of the underlying bonds
Which of Hudgens’s reasons for choosing bond mutual funds as an investment vehicle is correct?
选项：
A.Reason 1
Reason 2
Reason 3
解释：
B is correct.
Although a significant spread between the market price of the underlying fixed-income securities portfolio and an ETF’s NAV should drive an authorized participant to engage in arbitrage, many fixed-income securities are either thinly traded or not traded at all. This situation might allow such a divergence to persist.
你好，2的答案是不是有瑕疵？
“those discounts can persist.”
日常交易中，ETF的折溢价出现，一二级套利行为之下，这种折溢价怎么会一直persist？请问怎么理解？
