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. 

the answer  should be for MNIMAMAL.,
$(1+x)^3(1+x+x^2)(1+x+x^2+x^3)$ $=$ $x^8+5x^7+12x^6+19x^5+22x^4+19x^3+12x^2+5x+1$
hence,the answer will be 22
