$16-20$: True$/$False $-1$ point each $16.$ If you are short a put option that is exercised, and you are assigned, then you are required to buy the stock at the strike price. $17.$ A European option can be exercised only at the expiration date. $18.$ A call option gives the owner the right to purchase a fixed number of shares at a specified price, and to receive dividends paid during the life of the option. $19.$ A put option with strike price of $25$ is in the money if the spot price of the underlying asset is $30.20.$ Requiring a letter of credit or collateral is a way to protect oneself from counterparty credit risk.