There are three major factors that are related to the development of mental illness (biological, psychological, environmental). describe two biological causes that may influence the development of mental illness in an individual.(site 1)

Dementia and Delirium are two somewhat broad biological phenomenon that are biological causes of mental illness. These interfere with biological processes with the brain. If we wish to be more specific, Cancers, Alzheimer and Parkinson's Disease can affect the brain by pressing on important aspects (Brain Cancer's) and/or cause progressive degeneration (Alzheimer and Parkinson's)

“d” is the answer to the question

Starvation is bad because it makes your body unhealthy. if you don’t have a healthy diet you can age faster or even die before you’re 30.