Question

which biological factor may be involved in the development of mental illness?
○ infections
○ left - handedness
○ height - weight ratio
○ birth order in a family

Explanation:

Infections can impact the brain's functioning. For example, certain viral or bacterial infections during pregnancy or early childhood may disrupt normal brain development and increase the risk of mental illness later in life. Left - handedness is a normal variation in human motor skills and not a biological factor linked to mental illness development. Height - weight ratio is more related to physical health and body composition rather than mental illness. Birth order in a family is a social or environmental factor (related to family dynamics) rather than a biological factor in the context of mental illness development.

Answer:

infections