Which weakness was true of the alliances?

france and russia had deep hostilities for one another and the alliance was unlikely to last.
russia and germany previously had disagreements that were tough to settle.
both germany and austria-hungary quarreled with italy.
italy and serbia struggled to maintain alliances with austria-hungary.

The correct answer should be France and Russia had deep hostilities for one another and the alliance was unlikely to last.

Russians and Germans were not allies in WW1, and neither while Serbs and Italians were allies, they weren't allied with Austria-Hungary. France and Russia however did have wars historically and eventually the Bolsheviks had their revolution and abandoned the War and thus the French who fought in the War.