Number of ways selecting 4 letter words 
The number of ways of selecting 4 letters out of the letters MANIMAL

A. 16
  B. 17
  C. 18
  D. 19
I have made three different cases. Including 1 M, 2 M and none of the M.  
So it is 6C3/2 + 5C3 + 4C3 which doesn't meet any of the option. 

We can consider the number of pairs of repeated letters:
1) If there are no repeated letters, we have $\dbinom{5}{4}=5$ selections.
2) If there is one pair of repeated letters, we have $\dbinom{2}{1}\dbinom{4}{2}=12$ selections.
3) If there are 2 pairs of repeated letters, we have only 1 selection.
Therefore there are 18 possible selections altogether.
