Respuesta :

3. See if you count backwards from 10... (the odd numbers are in pranthesis)
10,(9),8,(7),6,(5),4,(3),2,(1)
and plus only 3 is an odd number out of those.

So 3 is the only answer 

4, 6 and 8 are all even numbers.

 the only odd number is 3

 so that is also the smallest.