The correct answer is- an ocean.
Central Asia is in general a dry region, occupied by deserts, steppes, dry plateaus, and this is due to the lack of precipitation because there isn't any large water body in its close surrounding area. The mountain ranges between the Central Asian region and the ocean also contribute to it being a dry region. The closest ocean to Central Asia is the Pacific Ocean, on the east of the region, and it is not close at all.