The mississippi river is a physical feature as it was discovered during a time where man weren`t capable of such construction in the earth.
The correct answer is - A. Devonian.
The Devonian is one of the seven periods of the Paleozoic Era. It lasted for 50 million years, from 410 million years ago until 360 million years ago. It is the period in which the first insects evolved, the first seeded plants, as well as the first land vertebrates. This period came after the Silurian period, and was followed by the Mississippian period.
