Texts from Strangers

"Ollie and the sister are cuddling with a woman in a striped skirt, presumably their mother, although presumptions about someone else's family are neither wise nor fair."

What does the word presumably suggest Strielstra is doing in the sentence?

She is making a false claim.

She is making a random guess.

She is making a factual statement.

She is making a reasonable assumption.

She is making a reasonable assumption.