The Main Reason That the Natufians Began to Settle Down

The main reason that the Natufians began to settle down into semi-permanent villages was that

A) western Asia became warmer and wetter.
B) the antelope and gazelle that they had hunted disappeared.
C) sea levels rose, flooding the coastal plains where they had lived previously.
D) a drier landscape meant that they had to be close to fresh water supplies in order to grow food.
E) a series of strong leaders wanted to control them more easily.