A: All of them.
In 2009, a group of institutions including Arizona State University lost a lawsuit because the universities had selected an e-reader for their textbooks that was (at that time) inaccessible by screen reading software (commonly used by blind and print-disabled individuals). As a result, the technology vendor updated their product, which is now accessible.
Since then, numerous cases have been argued and won against large and small universities (e.g., Louisana Tech, Penn State, U. California, Berkely, U. Montana) in the favor of legalized accessibility. All of these cases have involved either the institution’s technological infrastructure, actual course content, or physical environment.
Now, even the MOOCS are under scrutiny. MOOCS (massive, open, online, courses) typically are provided for free, have thousands of students, are open to anyone willing to register, and are non credit-bearing. Harvard and MIT are known for their high quality MOOCS, which are often podcast or video-lecture based. Advocates for the deaf are suing for closed captioning of these materials.
The moral of the story: consider inclusive design a necessary, cost-effective, and strategic part of developing tools and content for online learning.