Question

Which tower is more likely to fall?

Answer 1

I say B.  only because its smaller in width and it has a better chance of falling 

Answer 2

If there is no difference in angles but one has more width - this one is more likely to fall. 

In physics, we use term "center of mass" (geometrical point). 
The displacement of the center of mass from vertical line is higher => higher magnitude of net force => higher chance to fall.

I would say A :)