答案：A

unexpectedly 出乎意料地。例如：He unexpectedly failed to get the job.(他出乎意料没有得到这件工作。)又如：We met each other unexpectedly. (我们不期而遇。)deliberately故意地：I believe the house was deliberately set fire to.(我相信这房子是有人故意放火烧的。)reluctantly 不情愿地，勉强地：She agreed, very reluctantly, to help. (她十分买鸟枪地同意帮忙。) subsequently后来，随后：He escaped from prison but was subsequently recaptured. (他越狱逃跑了，但后来又被抓回来。)

本题译文：马戏团地老虎虽然已被驯服，但也会出乎意料地袭击驯兽师。