jack is attempting to replicate an experiment in which some baby mice were licked and nuzzled by their mothers constantly and some were neglected. Jack noted that when a mother mouse licks her newborn babies, that action reduced methylation of a gene, allowing increased serotonin to be released by the hypothalamus. The serotonin not only increased momentary pleasure but also started a chain of epigenetic responses that reduced stress hormones from many parts of the brain and body. Jack's subsequent experiments with the mice seem to indicate that the effects were lifelong. Jack's experiment seems to imply that:
a. every experience that a person has, especially in the early days and months, affects brain pattern.b. genetics is the decisive element in brain development.c. baby mice may show some delayed neuron growth but no lasting damage if normal nurturing proceeds after the experiment.d. rapid growth and refinement in axons, dendrites, and synapses occur in mammalian brains regardless of nature or nurture.

The new born mice was licked by their mothers that reduces some epigenetic changes in the new born. This licking help the mice to identify their offsprings and reduces the stress of new born.

The experiment that has explained in the question determines the effect of experience on the brain. The incident of the early days and months affects the individual brain pattern more severely than the incident occur in the later stages of the life.

Thus, the correct answer is option (a).