A period of exchanges between the
and
Worlds.

Explanation:

The Columbian Exchange

The Columbian Exchange refers to a period of cultural and biological exchanges between the New and Old Worlds.

operation overlord was the codename for the battle of normandy, the allied operation that launched the successful invasion of german-occupied western europe during world war ii. the operation was launched on 6 june 1944 with the normandy landings

answer; /// i believe that the correct answer is (d)the huang he river valley;