Question: What was the capital of the union of provinces in the Río de la Plata comprised by most of the former dependencies from the last to be organized and also the shortest-lived of the Viceroyalties of the Spanish Empire in the Americas?
Sentence (from "List of heads of state of Argentina"): It was the Primera Junta, a junta of several members, which would grow into the Junta Grande with the incorporation of provincial deputies.
Relevant evidence: No