How can environmental influences affect an organism's phenotype?

The correct answer highlights the relationship between the environment and the expression of an organism's genotype, which gives rise to variations in phenotypes. Environmental influences, such as temperature, availability of nutrients, light, and other ecological factors, can interact with the underlying genetic makeup of an organism to shape its physical characteristics and behaviors. This interaction means that two organisms with the same genotype may exhibit different phenotypes if they are subjected to different environmental conditions.

For example, consider a plant that has the genetic potential to grow tall but is stunted due to a lack of sunlight or water. The plant's environment has directly influenced its height, showcasing how environmental factors can lead to phenotypic variations.

The other choices suggest alternatives that do not accurately describe how phenotypes are formed in conjunction with environmental influences. Altering the genetic code or causing mutations would imply permanent changes to the DNA, which are different processes from how the environment affects existing genetic potential. Similarly, while reproductive success can be influenced by traits that may be affected by the environment, it does not directly address the immediate interaction between environment and phenotype expression.