1.Tm = 2 x (No.of G:C base pair) + 4 x (No.of A:T base pair)
2.Tm = 4 x (No.of A:T base pair) + 2 x (No.of G:C base pair)
3. Tm = 4 x (No.of G:C base pair) + 2 x (No.of A:T base pair)
4. Tm = 69.3° + 0.41 (%)G+C -650/1
Answer:3