anyone explain this to me??

[tonsonson]

plz explain it with ans~~i am not so sure

[VictorN]

Well, reading the http://en.wikipedia.org/wiki/Modular_arithmetic would be a good start!

[razzle]

i am not so sure

You only need to know that a = b mod m means a<m.

First have a look at proposition i. On the left side a+x must be smaller than m+m but on the right side b can be infinitely big so this proposition must be false.

Then have a look at proposition ii. On the left side a*x can be almost m*m but the right side can never be bigger than m so this proposition must be false too.

And that's enougth to declare alternative B the winner (if one of A thru E is true).