When graphing the phenotypes of a trait controlled by many genes and the environment, the line showing the frequency of each phenotype resembles ________.
a. A horizontal, straight line
b. A vertical, straight line
c. The letter T
d. A bell shape
e. A circle

Polygenic inheritance refers to the phenomenon where multiple genes contribute to a single trait, resulting in a continuous range of phenotypes. This type of inheritance is common for traits such as height, skin color, and weight, where each gene adds a small effect to the overall phenotype.

Phenotypic distribution describes how the various phenotypes of a trait are spread across a population. In cases of polygenic traits, this distribution often follows a normal distribution pattern, leading to a bell-shaped curve when graphed, indicating that most individuals exhibit intermediate phenotypes.

Environmental influence refers to the impact that external factors, such as nutrition, climate, and lifestyle, have on the expression of genetic traits. These influences can modify the phenotypic outcomes of polygenic traits, further contributing to the variability observed in a population.