Final answer:
The correct option is 4. The genetic phenomenon described by the production of wild-type offspring from two parents with the same recessive phenotype is called complementation, which is option 4.
Step-by-step explanation:
The production of wild-type offspring from a cross between parents that both display the same recessive phenotype illustrates the genetic phenomenon of complementation. Complementation occurs when two individuals with different mutations that produce the same phenotype produce offspring with a wild-type phenotype. This can happen if the mutations are in different genes that work in the same biochemical pathway or cellular process. Essentially, each parent provides a working version of the gene that the other lacks, restoring the wild-type phenotype in their offspring.
In contrast to other genetic concepts like incomplete dominance, where a heterozygous genotype creates an intermediate phenotype between the dominant and recessive phenotypes, and codominance, where both alleles for a trait are simultaneously expressed, complementation involves the interaction between different genes rather than different alleles of the same gene.
Moreover, epistasis occurs when the expression of one gene is affected by another gene, such as in the case of mouse coat color where one gene can mask the expression of a second gene. But in the case of the question, where crossing two parents with the same recessive phenotype results in wild-type offspring, complementation is the correct genetic phenomenon being described.
Therefore, the correct option for the phenomenon is 4) Complementation.