单选题：根据下面材料，回答题：A special research team from the local medical c

根据下面材料，回答题：
A special research team from the local medical center____ 76 ____experiments on completely blind babies. The babies to be tested on lived at home with their mothers of families. The rearch workers would visit the babies and closely____ 77 ____the development of their senses and behavior every two weeks.
In most ____ 78____,the research workers tested the responses of the blind babies to different stimuli(刺激) common in the family environment. Generally speaking, a ___79___ baby would react with smiles and laughter to tickling(瘙痒）,to the voice of a relative, and to hugging(拥抱）from his family. His reactions were swift.____80 ____, most of the blind babies, according to the experiments, responded to stimuli impassively In fact, they were indifferent to ____ 81 ____sound. But____ 82 ____some special situations, some of them were able to____ 83 ____to the sound of their mothers with a smile. Usually, their response was very____ 84____.
The tests were done about nine months; they____ 85 ____when the blind babies were one month old and ended when they were ten months old.
_______ A．carried
B．did
C．finished
D．took