Read this and answer the question. If the question is unanswerable, say "unanswerable".

Tajikistan is landlocked, and is the smallest nation in Central Asia by area. It lies mostly between latitudes 36° and 41° N (a small area is north of 41°), and longitudes 67° and 75° E (a small area is east of 75°). It is covered by mountains of the Pamir range, and more than fifty percent of the country is over 3,000 meters (9,800 ft) above sea level. The only major areas of lower land are in the north (part of the Fergana Valley), and in the southern Kofarnihon and Vakhsh river valleys, which form the Amu Darya. Dushanbe is located on the southern slopes above the Kofarnihon valley.

Which country is the largest nation in Central Asia by area?
unanswerable