Sport World’s September $55 call option sold for $0.50
Thus, you bought this contract for $0.50*100 share = $50. You could buy options that would give you the right to buy 100 shares of Sport World stock at a price of $55 per share from August until September.
If the stock price stayed below $55 during that period, you would lose your $50.
If it rose to $65, you could exercise a call option and your $50 investment would increase in value to ($65-$55)*100 shares = $1,000 in less than 30 days.