Which of the following can be altered through genetic engineering?

Genetic engineering refers to the direct manipulation of an organism's DNA to modify its characteristics. This technology is versatile and can be applied to both plant and animal DNA. By incorporating or altering specific genes, scientists can achieve desired traits, such as increased resistance to pests in plants or enhanced growth rates and disease resistance in animals.

The ability to modify genetic material allows for advancements in agriculture, including the development of genetically modified organisms (GMOs) that can improve food security and sustainability. For instance, scientists can engineer crops to withstand harsh environmental conditions or reduce reliance on chemical pesticides, showcasing the extensive applications of genetic engineering in both plants and animals. This makes the choice of both plant and animal DNA the correct answer, as it emphasizes the broad applicability of genetic engineering techniques across different biological systems.

Other options incorrectly suggest limitations by focusing solely on one type of organism or excluding both, which does not accurately reflect the capabilities and achievements in the field of genetic engineering.