When herbert describes the borders of new hampshire as " idea."- what does she mean?

Maybe when Christopher Herbert described the borders of New Hampshire as "an idea", he meant that people think of it that way since it serves as a 'gate' to the immigrants, mostly illegal, to create a new life, an ideally successful life beyond the border. 

Psychologists often talk of the magical number "7" - so it is generally assumed that we can keep 7 (more or less, so 5-9 is the correct answer) items in our short term memory - we know this as a result of many experiments.

we can increase this by chunking, so for example "7 8 9 5 3" is harder to remember than "78 95 3" - try it yourself!

the answer is a)