Final answer:
Ruth's return on the option is approximately 67%, calculated by dividing her profit of $200 by the cost of the option $300 and then multiplying by 100%.
Step-by-step explanation:
Ruth paid $300 for a call option to buy 100 shares of stock at $37 per share. The stock later rose to $42 per share. On exercising her option, Ruth would have paid $37 x 100 = $3,700 to buy the shares. She then sold them at $42 x 100 = $4,200. The return from the sale of the shares is $4,200 - $3,700 = $500. After subtracting the cost of the option, her profit is $500 - $300 = $200. To find the return on the option, we calculate (Profit/Cost of Option) x 100%, which gives us (200/300) x 100% = 66.67%, which is approximately 67%.