Apple’s popular news app has been aggressively promoting articles from left-leaning news outlets — even as it has all but shut down posts from more conservative publications, according to an explosive study. The Media Research Center, a conservative watchdog group focused on tracking media bias , analyzed a total of 620 stories that were featured by Apple News in high-traffic morning time slots between Jan. 1 and Jan. 31. The Apple News feed is curated by a team of in-house editors rather than