Which of the following statements about nuclear genome organization is CORRECT?

A、Nucleolar organizer regions are portions of chromosomes where ribosomal RNA genes are clustered and transcribed.;
B、Centromeres are sequences located at the ends of each chromosome.;
C、Telomeres are where sister chromatids adhere to each other and where spindle fibers attach during cell division.;
D、Chromosome organization is random in the interphase nucleus.