Both B and E are contenders
what is the grammatical reason to select (E) over (B)? Can someone please explain this?
Pulsars are generally believed to be fast-spinning neutron stars to be located by the pulsating radio waves
Choice B wrongly implies that neutron stars will be located by pulsating radio waves sometime in the future. The point in the sentence is they can generally be located. That is why, option E is better over B.
Hope it helps,
Never give up,,,