The right option is; A. They have been produced sexually.
A possible reason for this is because the puppies have been produced sexually. They are genetically unique, and similar to their two parents, but are not identical to either of them.
Sexual reproduction involves the combination of genetic information from two parents of different sexes to produce new organisms (offsprings). The genetic information is carried on chromosomes within the gametes (sperm in males, and eggs in females). During the process, the two gametes join together to form a zygote (in a process known as fertilization), which takes half of its DNA from each of its parents. The combination of the chromosomes in the zygote produces an offspring that is genetically unique, and similar to both its mother and father but is not identical to either.