Which of the following is a potential cause of mental retardation (intellectual disability)?

Genetic factors are a well-established potential cause of intellectual disability. Various genetic disorders, such as Down syndrome, Fragile X syndrome, and other chromosomal abnormalities, can significantly impact an individual's cognitive development and functioning. These genetic influences can result from inherited traits or mutations that disrupt normal brain development and functioning.

In contrast, the other options listed do not have a direct established link to the development of intellectual disabilities. Excessive exercise during pregnancy is not known to cause intellectual disability, and actually, maintaining a healthy level of physical activity is often encouraged. Consuming fruits and vegetables is associated with overall health benefits and does not contribute to developmental issues. Lastly, postnatal vaccinations are designed to protect children from serious diseases and are not linked to causing any form of intellectual disability; in fact, they play a critical role in child health and development.