SAT Question 177ed7dc: Words In Context answer and explanation

English - Words In Context - Fill In Blank Single Word
0:00
FREE OFFICIAL BANK
Though copies of The Adventures of Indiana Jones in Wenceslas Square in Prague on January 16, 1989—an underground computer game that was created anonymously in 1989 as an act of political protest against the authoritarian regime of what was then Czechoslovakia—were originally distributed ______, the game is now readily available online for anyone to play.
23
Difficulty:Hard
Which choice completes the text with the most logical and precise word or phrase?