There is no DNA in:
Mature RBCs
A mature spermatozoan
Hair root
An enucleated ovum
There is no DNA in mature RBcs (rich in haemoglobin) as their main function is to transport oxygen in the form of oxyhaemoglobin. So as to increase the oxygen binding affinity with haemoglobin they do not contain nucleus. Thus, the correct answer is option A.