Answer:
4dogs and no wolves
Explanation:
when a dog is taken care of (Trained) it could be let to run free in a definite region.
On a plane with one line we can place two dogs (one dog in each of the regions) and they will not fight as they will be separated by a line, and they will run free.
If we place three lines in general, then we would have four regions where 4 dogs can run free as they are separated by a line so as not to fight.
But for Wolves from the question it is deduced that: A wolf has to be caged all the time and no matter how well you train a wolve, it wont yield to instructions.
With these two, wolves wont be allowed on the plane at all.