Answer: B) transgenic organisms
Transgenic organisms are those organisms whose genome is incorporated with the foreign gene in order to manipulate or alter the genome. Such genomic manipulation or genetic engineering is done by using a micro injection which helps in incorporation or injection of foreign DNA into the fertilized egg of the surrogate mother. These mothers give birth to transgenic or genetically modified organisms.
According to the above description, In a test lab, several mice are injected with the gene that causes fireflies to glow. The mice are best identified as transgenic organisms.