我选C...这里主要是分辨due to的用法,还有它和owing to的区别:
1.先讲due to用法吧~
due to“由于,因…造成”,引导的短语在句中除可作状语（此时不用于句首）外,也可作表语或定语.有些情况下due to 可用于动词be之后作表语.目前普遍认为可将due to看作是owing to的同义词.
例句
Your failure is due to negligence.你的失败是由于疏忽所造成的.
Accidents due to driving at high speed were very common that weekend.在那个周末因高速驾驶造成的交通事故很多.
注意：due to除可表示原因外,还有“应给于,应属于”的意思.
例句
Our grateful thanks are due to you.向你表示我们衷心的感谢
2.所以现在这道题的选项也好解释了^-^
第一个空做"应给于,应属于"的意思,thanks做主语用复数谓语.所以是[are due to],排除B,D选项.
第二个空做"由于"的意思,简单的due to就好了~所以C应该是对的.
3.再讲一下due to和owing to的区别吧:
owing to引出的介词短语,在句中作状语或表语,做状语时,习惯上用逗号和句子其他部分分开,和due to 不同的是,owing to可以放在句首.
比如They decided to pospone the trip,owing to bad weather.由于天气不好他们决定推迟旅行.
Owing to his careless driving,we had a bad accident.由于他驾驶疏忽,我们发生了次大车祸.
（Cf:The accident was due to his careless driving.这次车祸是由于他的驾驶疏忽.）
有什么不懂可以继续追问^-^学习加油啊~