Final answer:
The main content of a document or webpage is the primary focus, the most important part, and contains the main message or information. Though not always in the center, it is often located there to capture attention readily.
Step-by-step explanation:
The main content (MC) of a document or webpage includes several true statements. Firstly, it is indeed the primary focus of a document or webpage. This means that the main content is what the creator of the document or webpage wants the audience to focus on the most. Secondly, it can be considered the most important part of the document or webpage because it holds the central message or information that is to be communicated.
Thirdly, the main content contains the main information or message of the document or webpage, which is typically the purpose of the document's existence. Lastly, while the physical location of the main content can vary, it is often found in the center of a document or webpage because this is where the eye naturally falls first, making it the most noticeable part for readers.