Answer:
b) Someone types the name of a website into a search bar and clicks the first link on the search engine results page
Step-by-step explanation:
Direct traffic can be described as when a user directly lands on your page without any referral site i.e search engines, blogs, etc.
when someone clicks on a link on an email, it is known to the user on which landing page he is going to visit, hence it comes under direct traffic.
when someone searches and clicks on the first result on the search engine page, it comes under referral traffic as it is being referred by the search engine.
when some directly visit the website from his bookmarks, it is under direct traffic as it directly lands on the website.
when a user searches by the URL in the address bar, it also comes under direct traffic, as the user pre-known the website and when searching on the address bar, it's directly gets landed on the website.
so, accordingly (B) is the most appropriate answer.