We take this oppommity to express our sincere ______ of your hel

We take this oppommity to express our sincere ______ of your help.
A、explanation
B、obligation
C、demonstration
D、appreciation
【正确答案】：D
【题目解析】：句意，我们利用这次机会，对于你及时的帮助，表达我们真诚的感谢。Anxiety焦虑 ambition抱负 association联合 appreciation感谢，根据题意，故选D。