Question

what is firefox?
a free and open source web browser designed by mozilla and released in 2004
a proprietary web browser designed by microsoft and released in 1995
an open source web browser designed by google and released in 2008
a proprietary web browser designed by apple and released in 2003

Explanation:

Firefox is a free and open - source web browser developed by Mozilla and first released in 2004.

Answer:

a free and open source web browser designed by Mozilla and released in 2004