Can someone help me with 2 things? one if this grammer looks correct and 2 with this problem on this articale The qustion is
Why did farming communities win the struggle for survival against hunters and gathers?

It's most likely choice a, it makes the most sense in my opinion.

Currently, as of february 2016, an american traveling in france would be by the exchange rate. the weakness of the euro and the strength of the us dollar means that items in france cost less to an american than they otherwise would. of course, if this trend reverses and the us dollar weakens and the euro strengthens, such as was happening in early 2008, an american traveling in france would have an adverse experience because items would cost relatively more.