(B)Wetter is answer....due to high rainfall
Answer:the first one is external stimulus
And the second one is migration
Explanation:
The mountain ranges and rivers in Southeast Asia have made a stripe like relief in the mainland of this region. The mountain ranges are in a north-south direction and separate the region into few big elongated valleys, and the 5 big rivers also are moving from the north towards the south (southeast, southwest as well), and are running in between the mountain ranges and cut through the valleys.
