37）有以下程序 # include main() {char p[20]={′a′, ′b′, ′c′, ′d′}, q[]="abc", r[]="abcde"; strcat(p, r); strcpy(p+strlen(q), q); printf("%d\n",strlen(p)); } 程序运行后的输出结果是 (A)9 (B)6 (C)11 (D)7