Answer:
environmental factors . . . biological factors
Step-by-step explanation:
The answer represents the seemingly most appropriate choice, however its a long debate and scientists believe that both environmental and biological factors can express the expression of a trait.
Environment is a sound factor that affects the expression of any trait. There are so many environmental factors such as Drugs,temperature ,chemicals and light that can affect the expression of a gene.
For instance, if a child has fair skin color by birth, but still he has dark color, it will be because of the enormous amount of time he spends playing outside in sun.
Now if we talk about biological factors like hereditary factors and genetics, they affect the personality traits of organisms to a great extent. Though environment also affects on personality but initial affect is solely due to biology. Personality includes all the traits including intelligence that make a man unique. Good genes of intelligence and physical appearance are clearly transferred to offspring and manifested in phenotype. However, environmental and cultural factors are still there and can reshape those traits in some way.
Hope it help!