To help the nervous system and brain develop.
Answer:
Phenotype
Explanation:
It's phenotype because a genotype is not a physical trait; a genotype means genes. It's phenotype because it a physical trait you can see. Lets say twins look the same on the outside but on the inside they have completely DNA. This is like how some butterflies look the same with orange wings but one might have a mutation in its genes.
The immune system helps guard against infection, protect from UV radiation, and regulate body temperature.
No; some mice may have developed lung cancer in less than 500 days of cigarette smoke exposure.
