Question 303599
Answer is B.9 

17 - 9 = 8 
There are reamining 8 cookies shared amongst the other two children. 

The combination of adding 8 are: 
1 + 7  
2+ 6 
3+ 5 
4 + 4 

All these numbers are smaller than 9. 

Therefore,the smallest possible number of cookies that Andrew ate has to be 9.