Helppppp! I just need a clarification.....

Note that

1111111=10^6+10^5+10^4+10^3+10^2+10+1

and

909091=10^6-10^5+10^4-10^3+10^2-10+1.

 

Compute the product of these two integers.

Is it a)10101010101010 or b)1010101010101?