Explanation:

- Auguste Comte (Option 1) was a founding figure of sociology and often discussed the early stage of social science, but the specific phrase is not widely attributed to him.

- A.R. Radcliffe-Brown (Option 2) is a famous British social anthropologist, but the cited statement is not commonly linked to him.

- John Millar (Option 3), a Scottish philosopher, contributed to the study of society but didn't use this phrase prominently.

- William Robertson (Option 4) was a historian, not particularly known for such a statement.

The statement “the science of human society is as yet in its extreme infancy” is most commonly associated with Auguste Comte, who highlighted the newness of social sciences.

Correct Answer:

Option 1: Auguste Comte