Which of the following traits can be influenced solely by environmental factors?

Phenotypic traits are characteristics of an organism that are influenced by both its genetic makeup and environmental factors. However, there are certain phenotypic traits that can be influenced solely by environmental factors, such as the effects of climate, nutrition, or soil conditions on plant growth. For example, the height of a plant can vary greatly depending on the amount of sunlight, water, and nutrients available, even among genetically identical plants.

Genotypic traits, on the other hand, are determined by the DNA of an organism and are not influenced by environmental factors. They refer to the genetic constitution of the organism, which remains constant regardless of external conditions. Neutrally selected traits, which might also be thought to relate to genetic variation, are those that do not significantly affect the fitness of an organism in its environment, and thus are not purely determined by environmental factors either.

In conclusion, the ability of environmental factors to influence phenotypic traits makes this the correct choice, as it highlights the dynamic relationship between an organism's traits and its surroundings.