Answer: alternative D.
Explanation: For the DNA to have the double strand structure, it is necessary to copy the sequence of the existing DNA strand in a complementary sequence of nucleotides, forming hydrogen bonds between them. The mRNA also uses this strategy when reading the DNA strand during the transcription, in order for the translation to begin.
Animals are used for food, products, and services.
The answer is alleles. In addition, the phenotype of an organism is the physical look resulting from the expression of the genes present. The principle of segregation states that substitute alleles for a trait discrete from one another throughout gamete formation and keep on distinct. A diploid organism that has two alike alleles for the same trait is named homozygous for that particular trait.