Most of the rainfall in this region falls

a. in central syria and western jordan.

b. in the rift valleys and the desert plateau.

c. in southeastern syria and eastern jordan.

d. on the highlands and the mediterranean coast.

In Syria and Jordan, most of the rainfall is on the West of the two countries, closest to the Mediterranean Sea. (so not in the East)

there is also a considerable amount of rain at the Golan Highlights, which are just West of the Jordan River, so in total the best answer is

d. on the highlands and the Mediterranean coast.