China’s factories suffered their fastest drop in activity in a year in April as new orders shrank, a private business survey showed on Monday, hardening the case for fresh stimulus measures to halt a slowdown in the world’s second-largest economy. The latest indication of deepening factory woes raises the risk that second-quarter economic growth may dip below 7 percent for the first time since the depths of the global crisis, adding to official fears of job losses and local-level debt defaults.