Natural gas futures slumped Monday as bullish traders closed out positions and took profits from the recent rally that has come in the face of weakening supply-and-demand conditions. Natural gas futures for April delivery ended down 4.1% at $1.8280 a million British thermal units on the New York Mercantile Exchange. Natural gas prices rallied 18% from a 17-year low early this month but have since given back more than 5% of those gains…