Explanation:

Let’s break down the options and what each thinker actually said about marriage:

- Malinowski

He’s best known for focusing on the family and kinship. He did talk about the importance of children in marriage, but he didn’t define marriage exactly as “a contract for the production and maintenance of children.”

- Westermarck

He looked at marriage in cultural and historical contexts. Westermarck's definition is more about social approval of sexual unions, not really about contracts or children specifically.

- Murdock

Here’s the thing—George Peter Murdock is the one who actually defined marriage as “a contract for the production and maintenance of children.”

- Taylor (Tylor)

He focused mostly on the origins of religion and culture, not marriage per se.

So, the correct answer is:

Option 3: Murdock