Alibaba’s billionaire founder resurfaced as he spoke to 100 rural teachers through a video call, three months after his last public appearance in October, sending the e-commerce firm’s shares up more than 8% in Hong Kong. A recording of the call was first posted on a news portal backed by the government of Zhejiang, the eastern province where Alibaba is headquartered, and the video was verified by an Alibaba spokesperson. Speculations swirled around Ma’s whereabouts after media reported in December that he skipped the taping of a TV program he…