市长在他的电视讲话中详细谈了交通安全问题。他提到自一月份以来，由交通事故造成的死亡人数一直在上升。 [

A、 ] The mayor dwelt at the problem of traffic safety in his TV talk, in which he mentioned the deaths caused by traffic accidents had been on the rise since January. [

B、 ] The mayor dwelt on the problem of traffic safety in his TV talk, which he mentioned the deaths caused by traffic accidents had been on the rise since January. [

C、 ] The mayor dwelt in the problem of traffic safety in his TV talk, he mentioned the deaths caused by traffic accidents had been on the rise since January. [

D、 ] The mayor dwelt on the problem of traffic safety in his TV talk, in which he mentioned the deaths caused by traffic accidents had been on the rise since January.