If the head of cockroach is removed, it may live for few days because:
a) the head holds a small proportion of a nervous system while the rest is situated along the ventral part of its body.
b) the head holds a 1/3rd of a nervous system while the rest is situated along the dorsal part of its body.
c) the supra-oesophageal ganglia of the cockroach are situated in ventral part of abdomen.
d) the cockroach does not have nervous system.