Explanation:

- Option 1: Physical contact

- This means being physically present or touching someone.

- Not all social relationships require physical contact (example: online friendships).

- Option 2: Face to Face contact

- This involves seeing each other in person.

- Many social relationships exist without ever meeting face-to-face.

- Option 3: Mutual awareness

- This is about both parties knowing the existence and presence of each other.

- This is the basic foundation or minimal requirement for any type of social relationship.

- Without mutual awareness, no interaction or relationship can begin.

- Option 4: Harmony

- This means peaceful and friendly relations.

- Harmony is ideal but not necessary at the start of a relationship.