One Reason Why We Think Neutron Stars Were Formed in Supernova

One reason why we think neutron stars were formed in supernova explosions is that

A) all supernova remnants contain pulsars.
B) pulsars are made of heavy elements, such as those produced in supernova explosions.
C) pulsars are often found near Cepheids and Wolf-Rayet stars, which are also signs of massive star formation.
D) pulsars spin very rapidly, as did the massive star just before it exploded.
E) pulsars sometimes have material around them that looks like the ejecta from supernovae.