Pulsars are generally believed to be fast-spinning
neutron stars to be located by the pulsating radio
waves it emits. (
A) to be located by the pulsating radio waves it
emits
(B) to be located by the pulsating radio waves they
emit
(C) locatable by the pulsating radio waves which it
emits
(D) emitting pulsating radio waves by which it can
(E) that can be located by the pulsating radio waves
they emit