問題補充：
單選題
President Hu cut short his visit to Latin America and returned to Beijing on Saturday ______ the 7.1-magnitude quake, ______struck the Tibetan Autonomous Prefecture of Yushu Wednesday morning, and left 1,484 dead with 312 still missing.A.due to; whichB.owing to ;thatC.as to ; whenD.thanks to; where
