In both Mesopotamia and Ancient China, the early civilization started A. in high mountains
B. near two rivers systems
C. on the ocean shore
D. around three big lakes

b. near two rivers tigres and euphrates river

classical republicanism, also known as civic humanism, is a form of republicanism  developed in the renaissance inspired by the governmental forms and writings of  classical  antiquity, especially such  classical  writers as aristotle, polybius, and cicero.

productive most commonly means: achieving or producing a significant amount or result.

explanation:

productive can also mean:

these depend on how the word productive is used. most likely productive will mean   achieving or producing a significant amount or result.