The answer is C: Crawler
The job of a search crawler and a web spider is the same. Actually, a search engine has many different names, such as automatic indexers and web spiders. A crawler is a program that browses the World Wide Web systematically in order to provide updated data to the particular search engine. Its purpose is to create entries for a search engine index. A crawler works by getting a list of URL’s to visit and store. It gets copies which it stores to the search engine to later index.