Some countries have several official languages because they want

a) make international diplomacy easier
b) foster political cooperation with neighboring countries
c) make government operate more efficiently
d) prepare students to participate in the global economy
e) give recognition to different groups within the country

It is beneficial, you learn a lot watching television. 

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)