参考答案：B

解析：

Both ETFs and closed end funds are closed to further direct investment (after initial public offer). Subsequent to IPO, they are only traded on an exchange. Their prices are determined by market supply and demand. While the price of closed end funds could be significantly different ( often lower) than NAV, ETFs often trade close to the net asset value of the underlying portfolio. With ETFs, new shares can be created and redeemed like a traditional open-end mutual fund (though only in very large lots). Thus, large institutional investors and market makers can arbitrage away much of the mispricing.