This question is missing the citation. I was able to find it online. It is the type that appears on a references page. I will not add it here only because it includes a website address.
Answer:
The significance of "11 Mar. 2013" is:
3. It shows when the researcher accessed the article.
Step-by-step explanation:
When we cite or reference an article found online, we should add the date of when we accessed it. Online articles can often be updated and edited over time. When you add the date, such as "11 Mar. 2013," you are letting your readers know that the article was a certain way on that specific date. However, if they access it later, the article may be different already.