The correct answer is N. The natural barrier crossed by the army of José de San Martín and Bernardo O'Higgins to liberate Chile from Spanish rule was the Andes.
The Crossing of the Andes was a set of maneuvers made by the Army of the Andes of the United Provinces of the Rio de la Plata (today's Argentina), between January 12 and February 8, 1817, to cross with a force of 4000 regular soldiers and 1200 militiamen the Andes mountain range from the Argentine region of Cuyo to Chile, and face the realistic troops loyal to the Spanish Crown that were there. It was part of the plan that General José de San Martín developed to carry out the Liberating Expedition of Argentina, Chile and Peru.
The crossing of the Andes is considered one of the great historical facts of Argentina, as well as one of the greatest feats of the universal military history.
