Explanation:

- The nuclear family typically consists of parents and their children living together.

- The extended family includes not only parents and children, but also other relatives like grandparents, uncles, aunts, and cousins living nearby or together.

- In the U.S.A. (Option 1), the nuclear family is the dominant family structure. Extended families living together are rare.

- In India (Option 2), extended families are still common, especially in rural areas.

- In Japan (Option 3), extended families have declined, but still exist.

- In China (Option 4), extended families may still be found, though the trend is toward nuclear families recently.

- The correct answer is: Option 1 - U.S.A.