The answer is the option B. Bolivian. Bolivia has historically been a single-product exporter country. In the past they exported tin and later silver. They continue having a mining based economy. Nowadays, their main commodities are gas and zinc. The market of tin collapsed in the '80s. Gold production and exports have increased enormously over the the past decade. Summarizing, by far the most important export product of Bolivia is gas, and they have increased the exports of other mining products like zinc, gold, silver. Other metals include antimony, iron and tungsten.