ACB
Aurora Cannabis Inc. Common Shares
stock NASDAQ

If you sell the contract you aren’t the one with any control in it being exercised, that’s the buyer. If you sell a naked call, it means you are willing to be exercised and sell 100 shares at your strike price (which could be a loss if that’s below your ACB of the shares).
If you sell a covered call it means you have 100 shares. Say they have an average price of 12$ purchase and you sold a 12.5$ covered call, the stock runs up to 15$ and you get assigned. You make 0.5$ per stock selling it at 12.5 plus whatever the original premium was. There is no issue.
If you sell a naked call it means you aren’t holding the stock as collateral. If you sell a 12.5$ call and get assigned when the stock is 15$ you will now be forced to effectively buy the stock at 15$ and selling for 12.5$ marking a 250$ loss (minus any premium collected). The further the stock runs the more your loss is. That’s why it’s unlimited upside risk since your losses will keep increasing indefinitely if the stock goes up. If you sold a covered call you already locked in your ACB (ideally below or near your strike) so that you have a very defined profit if assigned, whether the stock runs to 13,15 or 50.

If you sell the contract you aren’t the one with any control in it being exercised, that’s the buyer. If you sell a naked call, it means you are willing to be exercised and sell 100 shares at your strike price (which could be a loss if that’s below your ACB of the shares).
If you sell a covered call it means you have 100 shares. Say they have an average price of 12$ purchase and you sold a 12.5$ covered call, the stock runs up to 15$ and you get assigned. You make 0.5$ per stock selling it at 12.5 plus whatever the original premium was. There is no issue.
If you sell a naked call it means you aren’t holding the stock as collateral. If you sell a 12.5$ call and get assigned when the stock is 15$ you will now be forced to effectively buy the stock at 15$ and selling for 12.5$ marking a 250$ loss (minus any premium collected). The further the stock runs the more your loss is. That’s why it’s unlimited upside risk since your losses will keep increasing indefinitely if the stock goes up. If you sold a covered call you already locked in your ACB (ideally below or near your strike) so that you have a very defined profit if assigned, whether the stock runs to 13,15 or 50.