The phenotypic diversity observed within a population is primarily influenced by both genetic and environmental factors.

- Genotype refers to the genetic makeup of an individual, which provides the blueprint for potential traits. However, the way these genetic traits are expressed can be significantly modified by environmental factors such as nutrition, climate, exposure to toxins, and lifestyle. These environmental influences interact with the genotype to produce the final phenotype, the observable characteristics.

- It is important to note that random genetic mutations do contribute to genetic variation but are not the sole factor influencing phenotypic diversity at any given time. They are one of many sources of genetic variability that, combined with environmental effects, contribute to the diversity observed.

- Thus, the correct answer is: Option 3: Both genotype and environmental influences

Key points:
- Phenotype = Genotype + Environment
- Environmental factors can modify gene expression
- Genetic mutations contribute to variation but are not the only factor
- Phenotypic diversity results from complex interactions between genes and environment