Explanation:

Let’s break this down, option by option:

- Ogburn and Nimkoff: These two are well-known for defining family more in terms of social functions, like nurturing and socializing kids—not so much about the “sex relationship” bit.

- K. Davis: He talks a lot about family and its forms, but his definitions focus more on the functions rather than rooting the concept in sexual relationships.

- MacIver and Page: Here’s the thing, these scholars defined family as a group based on a “sex relationship sufficiently precise and enduring to provide for the procreation and upbringing of children.” The phrase almost matches word-for-word.

- Burgess and Locke: They saw family through the lens of interaction and relationships, more about the bonds and dynamics than strict sexual or biological factors.

So, the correct answer here is:

Option 2: K. Davis

What this really means is, K. Davis gave that specific definition tying family to a sex relationship for procreation and child-rearing. MacIver and Page defined family somewhat differently, not with this exact emphasis.