Explanation:

- Parsons (Option 4): Talcott Parsons is credited with the concept of the "isolated nuclear family." He discussed its role in modern industrial societies.

- Marx (Option 1): Karl Marx focused on class struggles and economic factors. He did not specifically address the nuclear family structure.

- Murdock (Option 2): George Murdock studied family structures across cultures but did not specifically coin "isolated nuclear family."

- Merton (Option 3): Robert K. Merton was known for his theories on social structure and functions, but not specifically for the nuclear family.