Annamese Cordillera, French Chaîne Annamitique, Vietnamese Giai Truong Son, principal mountain range of Indochina and the watershed between the Mekong River and the South China Sea. It extends parallel to the coast in a gentle curve generally northwest-southeast, forming the boundary between Laos and Vietnam.
The correct answer choice based on the graphs is B.) Farmers grew less cotton overall, and some gave up farming altogether. Each of the other answer choices would likely cause increases, not decreases in the pictured graphs. Hope this helped!