Final answer:
To find someone still alive on a family tree, social media profiles are often used as they provide current information, unlike birth, death, or marriage records that offer historical data.
Step-by-step explanation:
If we are looking for someone on the family tree who is still alive, we would use social media profiles. Social media platforms can offer up-to-date information about individuals and can help identify living relatives. This contrasts with other records like birth records, which provide historical data on births; death records, which catalogue individuals who have passed away; and marriage records, which document legal unions.
For instance, in conducting genealogical research or trying to find living relatives, social media can provide current photos, employment information, and even location data. While there are privacy concerns and limitations to this approach, social media profiles often serve as a useful resource for modern genealogists and family historians seeking contemporary connections.