Introduction:
RNA is a single-stranded nucleic acid that is transcribed from DNA during gene expression. In order for DNA to function properly, it must remove RNA molecules that are no longer needed. This process is carried out by specific enzymes known as DNA polymerases.

Options:
a) DNA polymerase 1
b) DNA polymerase 2
c) DNA polymerase 3
d) Primase

Explanation:
DNA polymerase 1, 2, and 3 are all enzymes involved in DNA replication. However, only DNA polymerase 1 has the ability to remove RNA primers. RNA primers are short nucleic acid sequences that are synthesized by primase during DNA replication. These primers are necessary for DNA polymerase to begin extending the DNA chain, but they must be removed once the chain is complete.

After the RNA primer is removed by DNA polymerase 1, the gap is filled in with DNA nucleotides by DNA polymerase 3. DNA polymerase 2, on the other hand, is involved in DNA repair and does not play a direct role in removing RNA molecules.

Primase is an enzyme that synthesizes RNA primers necessary for DNA polymerase to begin extending the DNA chain. While primase is involved in the synthesis of RNA, it does not have the ability to remove RNA molecules.

Conclusion:
In conclusion, RNA is removed by DNA polymerase 1 during DNA replication. DNA polymerase 2 and 3 are not involved in this process, and primase is only involved in the synthesis of RNA primers necessary for DNA replication.