Internet Explorer
Correct Answer: Cello

A brief explanation why…

Authored by Thomas R. Bruce of the Legal Information Institute at Cornell Law School, Cello was first released as shareware in June 1993 as the first and only web browser available at the time for Microsoft Windows. The operating system was popular among lawyers at the time and encouraged Bruce to create Cello so colleagues could access the Legal Information Institute's page (the first legal website, incidentally).

Bruce rewrote CERN's Unix-oriented WWW libraries to work on Windows and unlike other browsers of the day, he didn't borrow from Mosaic's source code, giving Cello a unique feel.

Although quickly accumulated 150,000 to 200,000 PC users, the final build of Cello was released in 1994 and by 1995 most computer users switched to browsing the web with Netscape or Internet Explorer.