The base pairing content for several DNA strands is reported below. Which strand would have the highest melting temperature (Tm)? Select one: A. 30% G-C B. 40% G-C C. 40% A-T D. 50% A-T E. 80% A-T

The base pairing content for several DNA strands is reported below. Which strand would have the highest melting temperature (Tm)?
Select one:
A. 30% G-C
B. 40% G-C
C. 40% A-T
D. 50% A-T
E. 80% A-T

1. 40% A-T
   Explanation:
   A-T base pairs are weaker than G-C base pairs
   DNA with high G-C content will have the highest melting point.
   According to chargaff’s rule, DNA sequence with X% A-T content, will have 100%-X% G-C content
   Among the above options, option C will have the highest G-C content because A-T content is taking 40% of the sequence bases, so G-C would be 100% – 40% = 60%