Answer:
a .Ans (linked)
b.Ans. (specifeid)
c.Ans ( singify something )
d .Ans (issue )
Explanation:

Search engines work by crawling hundreds of billions of pages using their own web crawlers. These web crawlers are commonly referred to as search engine bots or spiders. A search engine navigates the web by downloading web pages and following links on these pages to discover new pages that have been made available
Answer:
As per me C is the answer as you haven't post the essay to see the information.
Means someone or something is very light weight, metaphor