Which option strategy will not achieve its stated investment objective?

The correct choice involves understanding how different options strategies function and their intended objectives.

When you consider writing a put to protect a long stock position, it's important to recognize that this strategy doesn’t provide the intended protection. Writing a put option involves selling the right to someone else to sell you the underlying stock at a specified strike price. This can generate income from the premium received; however, it does not confer any protective benefits for a long stock position. If the stock price falls, the long stock position will incur losses, and the written put does not mitigate this risk, as it only creates an obligation to buy more shares at the strike price if the option is exercised. Therefore, this strategy does not fulfill the investment objective of providing protection.

In contrast, buying a put to protect a long stock position is safeguarding against downside risk. Writing a call to generate income does allow an investor to profit from the option premium while maintaining stock ownership, and buying a call can hedge against a short position effectively by providing the right to buy the stock back at a predetermined price. Thus, the other strategies listed achieve their stated objectives, while writing a put does not appropriately serve as protection for a long stock position.