Answer:
If the transgenic strain has the phenotype, then the gene fusion is functional, only in this case the copy of the gene is the gene fusion.
Step-by-step explanation:
OPTION A
The loss of function mutation is the mutation where the function of the gene is lost due to generally a point mutation. Here if in its place a second gene is transferred by means of specific genetic engineering, the inserted gene can be functional based on the length of the gene. There's certain carrying capacity of a genome to carry a gene.
Now if the inserted gene has a phenotype i.e the appearance in any sort or any secretory function, the gene can be checked to be functional. The gene can be partially functional if it's getting inhibited by any other gene present in the organism. But if there's no phenotypic appearance of the said gene, it's taken to be non-functional.