Which of the following can influence gene expression?

Gene expression can be influenced by a variety of factors, and the correct answer encompasses both genetic mutations and environmental factors.

Genetic mutations can directly alter the DNA sequence of a gene, which can impact how that gene is transcribed and translated into a protein. For instance, a mutation in the promoter region of a gene might affect how efficiently it is activated or silenced, thus altering the levels of gene expression.

In addition to genetic factors, environmental factors play a crucial role in gene expression as well. External conditions such as temperature, light, nutrient availability, and exposure to toxins can lead to changes in gene expression. These factors can interact with the organism's genetic makeup, leading to variations in how genes are expressed in response to the environment.

By integrating both genetic mutations and environmental influences, one can better understand the complex mechanisms of gene regulation and expression. This multifaceted approach reflects the reality that gene expression is not solely dictated by genetic factors but is also responsive to the surrounding environment. Thus, the answer correctly recognizes the combined contributions of both elements to gene expression.