Image is not available in the question so, the correct image is attached below.
Answer:
D. codes for a specific trait
Step-by-step explanation:
chromosome is defined as a DNA molecule found in the nucleus of most living cells which carry genes and transfer the genetic information.
The part labelled b in the image is gene. The function of gene is to code for a specific trait.
Genes are responsible for carrying traits that form the genotype and phenotype of an organism. where genotype shows the differences in genetic formation and phenotype shows observable characters in an individual such as color, height and features.
Hence, the correct option is D.