Question

Sympatric speciation is controversial because

a.
many scientists believe it is uncommon.

b.
many scientists believe gene flow would cause it to break down.

c.
the only well accepted mechanism for sympatric speciation is polyploidization.

d.
all of the above.

e.
none of the above.

Answer 1

http://www.sciencedirect.com/science/article/pii/S0960982206014102

Answer 2

still need help...

Answer 3

First of all, sympatric speciation is, to quote Wikipedia, "the process through which new species evolve from a single ancestral species while inhabiting the same geographic region".
In simpler terms, it is basically as if pterodactyls lived in, let's say, a desert area, like Saudi Arabia or Egypt. And so, "desert birds" evolved from the pterodactyls. (Note that none of this is true. It is just an example!) So, a new species evolves from an ancestral one, while still inhabiting the desert areas.
This may be controversial due to the fact that some scientists believe it is uncommon or just completely rare. It could also be because other scientists think that gene flow can break sympatric speciation down, since a species evolving from a single species can mean very bad things...and even failure to develop. That is why many species do not interbreed so often.
In all, I think it may be D, all of the above.
Hope this helps.