The correct answer to this open question is the following.
Although there are no options attached, we can say the following.
The natural feature that Abraham followed on the first part of the long journey to Canaan was a river in the Middle East region: the Euphrates River.
Abraham followed the bank of the Euphrates River on his way to Canaan.
Let's remember that Abraham lived in a Mesopotamian city called Ur. From Ur, he followed the river upstream. The distance? About 600 miles. He got to Haran which was located at the north of the River. From Haran, he traveled long until he reached Shechem.
