One Unit of a Peso in a Latin American Country

One unit of a peso in a Latin American country was defined as equivalent to 12 grains of "fine" (pure) gold, while one unit of its neighboring countries currency, a dollar, was defined as equivalent to 18 grains of "fine" (pure) gold. Using the gold par value concept (with 480 grains in an ounce) , the exchange rate for converting the peso to the dollar is

A) 1.5 peso = 1 dollar.
B) 1 peso = 1 dollar.
C) 3 peso = 2 dollar.
D) 1 peso = 1.5 dollar.
E) 2 peso = 1 dollar.