new to options, why would AUG 15 options be listed on Yahoo on August 23??? this is likely a simpel answer
August 21, 2015? I see August 28, 2015 options but not any previous weeks. Try reloading your browser, Yahoo usually discontinues option listings within hours of expiry.
Most Active by Volume and when you click the link to one of the expired options "There are no results for the given search term."