Check this post out on some approaches in delaing wiht remainder questions:

https://www.beatthegmat.com/understandin ... 33535.html

For this problem:

To find : N/6 the remainder or basically is N divisible by 6 then we know the remiander is 0 or what are the possible values of N and does the remainder when divided by 6 stays the same(i.e w eneed to find one single remiander value)

Stmt I

N is a multiple of 5 can be expressed algenrically as N = 5*K
where K is an integer.

if k=0 n=0 remainder is 0
if k=1 n=5 reminder when n divided by 6 is 5

INSUFF (since we many different remainder values are possible)

Stmt II

N = 12K

Since 12 is divisible by 6 with a remainder 0 we know N is definitely divisble by 6 so the remainder is always going to be 0

SUFF

Choose B

Hope this helps!

Regards,
CR