DNA is a polymer of nucleotides which are linked to each other by 3’-5’ phosphodiester bond. To prevent polymerisation of nucleotides, which of the following modifications would you choose?
1. Replace purine with pyrimidines
2. Remove/Replace 3' OH group in deoxy ribose
3. Remove/Replace 2' OH group with some other group in deoxy ribose
4. Both ‘b’ and ‘c’