Which of the following statements about ribosomes and ribosomal RNA is NOT true?

A) Ribosomes typically contain about 80% of the total cellular RNA.
B) Ribosomal RNA is processed in both prokaryotes and eukaryotes.
C) In eukaryotes, genes for rRNA are usually present within tandem repeats.
D) Each ribosomal RNA component is encoded by a separate gene.
E) In eukaryotes, the rRNA transcripts are processed further by snoRNAs within the nucleus.