Natural-gas prices fell Thursday as investors began to contemplate how much natural gas will be added to storage as spring begins. Futures for May delivery settled down 4 cents, or 1.24%, at $3.191 a million British thermal units on the New York Mercantile Exchange, snapping a two-session winning street. The U.S. Energy Information Administration reported that natural-gas supplies fell by 43 billion cubic feet last week. That…