Step 1: Look at what is being asked.
Count the married couples living together. More than one related couple means it is not nuclear. We will work it out by sorting the choices one at a time.
Step 2: Working through the choices, part 1.
Focus on the number of married couples in the home. There are more than two brothers, so there are more than two couples with children.
Step 3: Working through the choices, part 2.
One couple with children would be a nuclear family. Here there are many couples, so choice 1 is out.
Step 4: Working through the choices, part 3.
Matrilocal and patrilocal talk about whose home the couple moves to after marriage. They do not name a family structure of brothers. So choices 3 and 4 are out.
Step 5: Working through the choices, part 4.
A group of related couples and their children in one household is called an extended family. So choice 2 is in.
Final Answer:
Many related couples together make an extended family, so option 2 is the answer. \[ \boxed{\text{Option 2}} \]