31 A&C are behind the left emergency exit. So there are no seats in front of that part of row 31. This makes row 31 an "Exit Row". The rest of row 31 is behind row 30 D - G. There are no row 30 A&C seats. If you look at the seating map you will understand. 31 G will not have the problem of people crossing in front of you as in 30G, but 31 G is right next to the toilet so you will have people walking by you on your right side to get to the toilet. If less foot traffic is your main concern, stay on the left side of the cabin, if access to the toilet is your main concern, pick a seat on the right side. Simple as that.