A crawler based search engine refers to a software that maintain searchable databases of web pages and which organised those pages for users in a valuable manner. An example of crawler based search engine is Google. The search words or phrases that a user input into a craw based search engine is used to retrieve relevant information from the software databases based on the in-built index structure.
<h3>I say this because if it is asking about "feeling" then the mood relates. I do not agree with a or d.<u> B maybe but please let me know if I'm wrong!!!</u></h3><h3 /><h3>Hope that helps! :)</h3>