c.) options with optional
 default values and the ability to affect the resource disk cache key used by <a href="../../../../com/bumptech/glide/load/engine/DiskCacheStrategy.html#RESOURCE"><code>DiskCacheStrategy.RESOURCE</code></a>.

 <p>
   Implementations must either be unique (usually declared as static final variables), or
   implement <a href="../../../../com/bumptech/glide/load/Option.html#equals-java.lang.Object-"><code>equals(Object)</code></a> and <a href="../../../../com/bumptech/glide/load/Optio