The synthesis of Okazaki fragments is a key element in DNA replication. Each Okazaki fragment is initiated by an RNA primer. The RNA primer is made complementary to the DNA template strand in the 5'-3' direction by an enzyme called primase using RNA nucleotides. How are they removed from the Okazaki fragments as well as from the leading strand?

a )After an Oakzaki fragments has been synthesized by the DNA polymerase III, the RNA primer is removed by the 5'-3' exonuclease activity of DNA polymerase III
b) After an Oakzaki fragments has been synthesized by the DNA polymerase III, the RNA primer is removed by the 5'-3' exonuclease activity of DNA ligase
с) After an Oakzaki fragments has been synthesized by the DNA polymerase III, the RNA primer is removed by the 5'-3' exonuclease activity of primase
d) After an Oakzaki fragments has been synthesized by the DNA polymerase III, the RNA primer is removed by the 5'-3' exonuclease activity of DNA polymerase