China’s economic growth held to a 6.4% rate in the first three months of the year as factory production picked up significantly amid signs authorities worked forcefully to stabilize business following months of weakness. The 6.4% expansion in China’s economy during the first quarter was the second straight at that level but remained below 2018’s 6.6% full-year rate, according to official data released Wednesday. The pace was slightly higher than what many economists expected and appeared buoyed by a powerful rebound…