Final answer:
Transposable elements, which make up 45% of the human genome, are thought to serve the function of genetic mobility. They contribute to genetic variability and can indirectly affect gene expression, which is critical for various cellular functions including protein synthesis.
Step-by-step explanation:
The question asks about the function of transportable elements, which account for 45% of the human genome. Among the provided options, C) Genetic mobility is thought to be their function. These elements, also known as transposable elements or transposons, have the ability to change their position within the genome, a property that contributes to genetic variability and can have various consequences, including the regulation of gene expression.
It is understood that the DNA provides the blueprint for cellular structure and function, with genetic information necessary to build proteins that are essential for structural components of the cell and for biochemical reactions, including enzyme functions involved in metabolism and energy production. While transposable elements might not have a clear role in providing structural support, energy production, or direct metabolic regulation, their mobility within the genome can have indirect effects on these aspects by affecting the genetic information over time.