The correct answer is SCIRUS.

• Scirus is the most comprehensive science-specific search engine on the Internet.
  • This web search engine focuses only on those sites and journal databases with scientific content highlights peer-reviewed articles and covers over 100 million science-related pages.
• It launched in 2001.
• ScienceDirect is operated by the British-Dutch publisher Elsevier. It was launched in March 1997.

• Google LLC is an American multinational technology company that includes online advertising technologies, a search engine, cloud computing, software, and hardware.
  • The current CEO of Google is Sundar Pichai.
  • Google was founded on 4 September 1998, Menlo Park, California, United States.
  • Parent organization: Alphabet Inc.
  • Larry Page and Sergey Brin were the founders of Google.
• Yahoo!, which includes features such as a search engine, an e-mail service, a directory, and a news branch, began as a simple collection of Yang and Filo's favorite Web sites.
  • The current CEO of yahoo is Marissa Mayer.
  • Yahoo was founded in January 1994, Sunnyvale, California, United States.
  • Parent organization: Verizon Media.
  • Founders: Jerry Yang, David Filo.
• AltaVista was a Web search engine established in 1995.
  • Founder: Louis Monier.
  • Headquarters: Palo Alto, California, U.S.