选that.句意：他没来/没出现,结果他很生气.（前后he应该不是同一人）
此处从句不缺主语、宾语,故排除代词which和what.
that在此的用于引导状语从句,表示结果,意为：以至于.
引导的连词有结果状语从句：that,so (that),so/such…that等.通常置于主句之后.so that最为常用,so或that常用于口语或非正式文体中.
What has happened that you look so worried发生了什么事,使你显得如此担心?