Why are sibling relationships likely to become more important in late adulthood?

Why are sibling relationships likely to become more important in late adulthood?
A) Siblings typically provide practical assistance to each other, such as help with activities of daily living.
B) Most older adults expect to live with siblings when health problems or disabilities, such as arthritis or diabetes, occur.
C) Siblings share reminiscences and companionship and provide each other emotional support.
D) In late adulthood, relationships with siblings are typically less stressful and have less conflict than relationships with adult children or spouses.