To answer this question, the user needs to have knowledge about the history of web browsers. The first web browser ever built was developed by Sir Tim Berners-Lee and his team at CERN (the European Organization for Nuclear Research) in Switzerland in 1990. It was called the WorldWideWeb.

Now, let's go through each option and explain why it is right or wrong:

A. World Wide Web: This option is incorrect because the WorldWideWeb was not just a browser, but also an editor and a server. It was the first web browser ever built, but it was not called the World Wide Web browser.

B. Mozilla Navigator: This option is incorrect because Mozilla Navigator was not the first web browser ever built. It was developed by Netscape Communications Corporation and released in 1994, after the WorldWideWeb.

C. Internet Explorer 1.0: This option is incorrect because Internet Explorer 1.0 was released in 1995, after the WorldWideWeb and Netscape Navigator.

D. Netscape Navigator: This option is incorrect because Netscape Navigator was not the first web browser ever built. It was developed by Netscape Communications Corporation and released in 1994, after the WorldWideWeb.

Therefore, the correct answer is: A. World Wide Web.