IMO E
A) not sufficient. there are many possibilities
B) Not possible-because many possibilities

combining 1 and 2
if both m and r are positive
m=6,r=18
but there is one more possibility. when m is negative and r is positive
m=-12,r =36

what is r?

Statement 1: The distance between r and 0 is 3 times the distance between m and 0

In absolute terms, this means: |r| = 3|m|, and from this you have the following possibilities:

i) r = 3m
ii) r = -3m

It is evident from here that even if we know m, we cannot solve for r. Insufficient.


Statement 2: 12 is halfway between m and r

If a number is halfway between two other numbers (say a and b), then essentially this number is also the average of a and b. So,

12 = (m + r)/2
24 = m + r

Once again, without sufficient knowledge of m, we cannot solve for r. Insufficient.

Both statements together:

if r = 3m, then 24 = 4m and m = 6, r = 18.
if r = -3m, then 24 = -2m and m = -12, r = 36.

Insufficient. Choose E.

-BM-