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:

To determine the biological factor in mental illness development, we analyze each option:

• Infections: Biological agents (like viruses/bacteria) can impact brain function and contribute to mental illness (e.g., infections affecting the CNS).
• Left - handedness: Aneural/anatomical trait, not a direct biological factor for mental illness.
• Height - weight ratio: Related to physical health, not a core biological driver of mental illness.
• Birth order: A social - family dynamic, not biological.

So infections are the biological factor.

Answer:

A. infections