Which of the following statements is most likely an incorrect statement?

Most ETFs track a stock index; those that track a bond index or invest in commodities, such as gold, are not that common.

ETFs have expense ratios that are typically lower than those of the average mutual fund.

Unlike mutual funds, ETFs are traded on a stock exchange, provide the ability to sell short and buy on margin.

An ETF is a type of fund that divides ownership of itself into shares that are held by shareholders and invests in stocks, commodities, or bonds.