Complex sentence: A total of six cargo ships from China Merchants Steam Navigation Company were selected for the conversion, all of which were American coastal freighter of World War II era, which were sold to China Merchants Steam Navigation Company after the war.
Split into simpler sentences: A total of six cargo ships from China Merchants Steam Navigation Company were selected for the conversion, all of which were American coastal freighter from the World War II era. These ships were sold to China Merchants Steam Navigation Company after the war.