Indicate Whether Each of the Following Descriptions Better Applies to the Genome

Short Answer

Indicate whether each of the following descriptions better applies to the genome of mitochondria (M) or nuclei (N) in vertebrates. Your answer would be a four-letter string composed of letters M and N only, e.g. MNMN.
( ) It has a higher percentage of noncoding DNA.
( ) It has a stricter codon usage.
( ) Its genes are present at higher copy numbers per cell.
( ) Its evolutionary clock ticks much faster.