Both ETFs and closed-end funds can be bought and sold on the open market. This is a key characteristic of these types of funds, distinguishing them from mutual funds, which are bought and sold through the fund company. ETFs and closed-end funds are listed on stock exchanges and their shares are traded like stocks. This provides investors with the flexibility to buy and sell shares at any time during market hours, unlike mutual funds, which can only be bought or sold at the end of the trading day at the NAV price.

Choice B is incorrect. While it is true that both ETFs and closed-end funds can be bought and sold on the open market (Statement III), Statement I is not accurate for all cases. Not all ETFs and closed-end funds are passively managed to match a specific index. Some may be actively managed, depending on the fund's strategy.

Choice C is incorrect. Again, Statement I is not universally true as explained above. Additionally, while it's possible for the market price of shares and the net asset value (NAV) to significantly differ in both ETFs and closed-end funds (Statement II), this tends to occur more frequently with closed-end funds due to their fixed share structure.

Choice D is incorrect. As explained above, Statements I and II are not universally true for all ETFs and closed-end funds, making this option invalid.