下列哪个消息用语表示具体确切的消息来源?
A: A French nutritionist was quoted as saying that…
B: It is reported that…
C: The Swedish Radiation Protection Research Institute says…
D: It was learnt that…
A: A French nutritionist was quoted as saying that…
B: It is reported that…
C: The Swedish Radiation Protection Research Institute says…
D: It was learnt that…
