The first major city in the western hemisphere was located in which country?

Mexico City in Mexico

Explanation: Mexico City is a city located in current day Mexico. The city has been inhabited from as early as 100AD.

The Toltecas were among the earliest inhabitants of Mexico City, among its early inhabitants were the popular Aztech tribe with their early forms of Technology.

answer; ///i believe the correct answer is (a) decrease biodiversity;