I checked my rig , sat in my seat and took the oars . Time to focus . Big water lay waiting downstream , a string of serious and reverent names like Horn Creek , Granite , Hermit and Crystal . As our group pushed off and my boat swung out into the Bright Angel riffles , I started to sing Do n't Fence Me In , and , you know , I think I never sounder better .
According to the above context, choose the best option to answer the following question.
Question: What may be the reason why they were singing so good ?
Options:
A. Because they were trying .
B. Because they have been watching videos on learning how to sing .
C. Because they had special training .
D. Because they were relaxed .


D