There are two versions of the embed code on SlideShare. We recommend you use the new version that starts with <iFrame…>. You can access the new (iFrame) embed code by clicking on the Embed button on the top bar of the player. See the screenshot below:

If you are embedding in a Wordpress blog, you can use the new iFrame code for Wordpress.org blogs, or use the Wordpress short code if you have a Wordpress.com blog. 

This is the view after clicking on the Customize link: