RNA is a labile molecule due to the presence of:

2'-OH group

The correct answer is Option (4) → 2'-OH group

2'-OH group present at every nucleotide in RNA is a reactive group and makes RNA labile and easily degradable. DNA lacks the 2'-OH group that makes RNA more reactive. RNA is also now known to be catalytic, hence reactive. Therefore, DNA chemically is less reactive and structurally more stable when compared to RNA. Therefore, among the two nucleic acids, the DNA is a better genetic material. In fact, the presence of thymine at the place of uracil also confers additional stability to DNA. Both DNA and RNA are able to mutate. In fact, RNA being unstable, mutate at a faster rate. Consequently, viruses having RNA genome and having shorter life span mutate and evolve faster.