Answer:
B). The name of the website.
Step-by-step explanation:
As per the guidelines of Modern Language Association(MLA), the citation of a webpage usually begins with 'the author's name followed by the title of the page or website, publisher, publishing date, and lastly the URL and the date of access.'
Since the author's name is not provided in the given entry, the information that must be listed first in the citation would be 'the title or name of the website'(by skipping the author's name') followed by other details as mentioned in the above format. Thus, the final entry of the source would read as:
""A Day for Trees", U.S. Department of Agriculture, 10 Jan. 2014. www.arborday2014.org . Accessed 18 April 2014."