Understand the relationship between chromosome numbers in different cell types.

Man:

• Humans have a diploid number ($2n$) of 46 chromosomes in somatic cells and a haploid number ($n$) of 23 chromosomes in gametes.
• The given value for "Cardiac muscle" for Man is 3. This is biologically incorrect for the total number of chromosomes in a human cardiac muscle cell, which should be 46. Assuming this is an error in the question, we will use the correct biological value.
• Sex chromosomes ($n$): 23
• Skin ($2n$): 46
• Cardiac muscle ($2n$): 46 (using the correct biological value)

Mouse:

• Given: Sex chromosomes ($n$) = 20.
• Diploid number ($2n$) = $2 \times 20 = 40$.
• Skin ($2n$): 40
• Cardiac muscle ($2n$): 40

Rhesus monkey:

• Given: Skin ($2n$) = 42.
• Haploid number ($n$) = $42 / 2 = 21$.
• Sex chromosomes ($n$): 21
• Cardiac muscle ($2n$): 42