Analyzing Business Structure

I wrote a post for my discussion in class, but my professor replied with the questions below:

What sort of legal entity is Walmart? Is it a corporation, LLC, a partnership, or something else. Being a multinational organization I suspect it has many subsidiaries. What sort of legal form are these subsidiaries? Why did Walmart select this particular form of entity? This is the essence of this discussion question. What do you think?

We are discussing analyzing business structures and I chose Walmart. What is the best way to reply to his questions? Thank you!