What are small segments of DNA that code for proteins and determine traits called?

The correct answer is genes. Genes are specific sequences of DNA that code for proteins, which play a crucial role in determining the traits and characteristics of an organism. Each gene contains the necessary information for the production of a particular protein, and these proteins are responsible for various functions and features in the body, such as eye color, height, and susceptibility to certain diseases.

Understanding the role of genes is fundamental in genetics and biology, as they are the basic units of heredity passed from parents to offspring. This concept is distinguished from alleles, which are different versions of a gene that can result in variations of a trait, and from chromosomes, which are long strands of DNA that contain many genes. Genotypes refer to the genetic makeup of an organism, which includes all its genes. Therefore, the term 'genes' specifically identifies the segments of DNA that directly encode proteins and influence traits.