Elementary Matrix Problem 
I suspect A and C to not be elementary matrices. However, I'm not sure which one. I'm simply confused regarding the diagonal placement in a) and c). Would you need more than 1 elementary row operation to achieve such matrices (A) and (c)? 
EDIT: This was a careless mistake, I overlooked that row operations can be swapped. 

Remember that swapping rows is an elementary row operation.  If you swap the first and third row of the identity matrix, you will get matrix A.  
