Final answer:
Close relationships are differentiated from casual relationships based on factors such as proximity, similarity, and self-disclosure.
Step-by-step explanation:
Close relationships are differentiated from casual relationships based on several factors such as proximity, similarity, and self-disclosure. Proximity refers to the physical or geographical closeness between individuals, which makes it easier to form relationships with people we see frequently. Similarity is another important factor, as we are more likely to be friends or romantic partners with those who share similar background, attitudes, and lifestyle. Self-disclosure, or the act of revealing personal information to others, also plays a role in forming close relationships as it deepens the connection between individuals.