Hi Jen!
Your arrow diagram there looks good, including the part with "
far from rivers" at the end. The stimulus basically tells us that early urban societies needed large-scale farming, which needed irrigation, which (at the time) needed to not be far from rivers or lakes. That's a great diagram to arrive at correct answer choice (C).
That middle sentence is not actually specific to foraging--that's just an example of methods of food acquisition besides large-scale farming. So if I was going to diagram that middle sentence, I would actually diagram it as:
large-scale farming maintain early urban societies
That's really just the contrapositive of your first statement so it isn't actually adding any new information to our contrapositive chain.
In general, however, you may sometimes encounter conditional statements that do not connect to your other conditional statements, or that at least don't connect in a way that allows you to make any inferences between conditions. So be careful not to assume that just because you have an extra conditional statement that it must fit at the beginning or the end of your chain. Sometimes it's just extra information that doesn't give you any inferences.
Hope this helps!
Best,
Kelsey