Three of Hong Kong’s most prominent pro-democracy activists and six others went on trial Monday for spearheading the tumultuous “Occupy Central” demonstrations in 2014. The case is the most concerted effort yet to punish the leaders of mass protests that immobilized the city’s financial district for nearly three months and drew global attention to China’s stifling of democratic norms and political rights in the semi-autonomous territory. About 100 people joined the nine defendants at a rally outside the courthouse before the trial began Monday.