EROM x 9 = MORE

To prevent confusion between the letter O and the digit 0 (zero),
let's change the letter O to the letter A, then when we write "0",
we will know it is a zero, and not the letter O.

       ERAM * 9 = MARE

Change 9 to 10 - 1 

  ERAM*(10 - 1) = MARE
  ERAM*10- ERAM = MARE
        ERAM*10 = MARE + ERAM

When you multiply ERAM by 10 you annex a zero on the right end,
getting ERAM0, so

         ERAM0 = MARE + ERAM

Write that as an addition in vertical fashion, letting x, y, 
and z be the numbers to carry, which can only be 0 or 1
 
       x y z
       E R A M
      +M A R E
     ---------
     E R A M 0  

E is obviously 1, since x+E+M could not possibly add to
more than 18 even if they were large as possible.  So we have:

       x y z
       1 R A M
      +M A R 1
     ---------
     1 R A M 0 
 
Looking at the rightmost column, M is obviously 9, with a 1 
to carry, so z=1, and now we have:

       x y 1 
       1 R A 9
      +9 A R 1
     ---------
     1 R A 9 0  

x could not be a carry of 1, for that would make R=1, 
but E is already 1, so R=0 (zero), and x is 0 to carry,
so now we have:

       0 y 1 
       1 0 A 9
      +9 A 0 1
     ---------
     1 0 A 9 0  

In the next to the rightmost column, A is obviously 8, 
making y=0 to carry, so we have:

       0 0 1          
       1 0 8 9
      +9 8 0 1
     ---------
     1 0 8 9 0  

Now we compare that to 

       x y z
       E R A M
      +M A R E
     ---------
     E R A M 0 

E=1, R=0, A=8, M=9, x=0, y=0, z=1

So the answer to

ERAM x 9 = MARE  

is 

1089 x 9 = 9801

The problem only asked for the value of R, so the answer is 0 (zero),
choice B)

Edwin