[OS X TeX] Detecting an option in documentclass [OT]

[Themis Matsoukas]

This is a pure latex question: is it possible to detect an option in a document class? For example, in some files I use

\documentclass[11pt,article]{memoir}

and in others

\documentclass[11pt]{memoir}

I am building a macro that should behave differently depending on whether or not the option "article" is loaded. 

Thanks.