The correct answer is a.: specific.
This structure (this +adj) requires an adjective and the only adjective is in a., the other options are verbs or nouns and are not correct.
Answer:
What is a search engine and what is its function? Search engines function on the Internet by allowing Internet users to find specific information from the Web based on keyword criteria that is entered by the user. Each search engine has a crawler that projects into the Internet to follow hyperlinks and gather information from Web pages.
The scar symbols analysis and the creepers are actually that grow all over the island
