In the DNA molecule:

1. A
   There are two strands which run antiparallel — one in $5^{\prime }\to 3^{\prime }$ and other in $3^{\prime }\to 5^{\prime }$
2. B
   The total amount of purine nucleotides and pyrimidine nucleotides is not always equal
3. C
   There are two strands which run parallel in the $5^{\prime }\to 3^{\prime }$ direction
4. D
   The proportion of Adenine in relation to Thymine varies with the organism