What problems still exist in using natural regeneration?

Natural regeneration of forests and woodlands is the process by which new trees grow from seeds that have fallen and germinate where they have fallen.  The biggest problem with natural regeneration is that is unpredictable.  As a result, it cannot be used for commercial farming. For most of the last two or three hundred years, forests and woodlands have restocked by using transplants grown in nurseries. The young trees are planted in equidistant rows. This allows each tree the best possible change of optimal growth. 

The answer would be c, white eyes are homozygous recessive. in the early 1900s, morgan conducted several experiments with vinegar  flies (drosophila). one  sample revealed an anomaly: a  white-eyed, single male fly. he attempted to breed this fly with the typical red-eyed females. the offspring were all red-eyed. using flies from this new generation (brother-sister pairs)  produced some red-eyed and a few white-eyed flies. the white-eyed were all male. in later experiments, he was able to produce white-eyed females. this proved that white eyes are not lethal to either sex (ruling out a and b). since the percentage of white eyes to red eyes is so low, white eyes are not a dominant trait. it would be a recessive trait.