Final answer:
The non-violent movement from Yoav Tenembaum's article that was not ultimately successful before the fall of communism was the Solidarity movement in Poland.
Step-by-step explanation:
Out of the three examples of non-violent movements given in Yoav Tenembaum's article, the one that ultimately was not successful was C. Solidarity movement in Poland. Each of the other movements listed—the civil rights movement in the U.S., Indian independence movement, and the anti-apartheid movement in South Africa—achieved significant change through nonviolent tactics such as protests, boycotts, and moral suasion.
In contrast, while Solidarity in Poland played a crucial role and made significant inroads, it encountered ongoing resistance from the government, and it wasn't until the fall of communism that the movement could be considered ultimately successful.