When Neutron Stars Were First Predicted Theoretically, No Scientist Expected

When neutron stars were first predicted theoretically, no scientist expected to be able to detect one of them across interstellar distances. What enabled astronomers to find neutron stars in the late 1960's?

A) they give off a lot more light than expected, and can be seen glowing with a reddish light from far away
B) they are so large, their dark outline block a significant amount of starlight from behind them
C) we found strongly magnetic neutron stars whose whirling beams of energy were detected as pulsars
D) some neutron stars soon collapse to be white dwarfs, whose light can be detected further away
E) astronomers have actually only found one neutron star and that was discovered very close to us and by sheer luck