If the head of a cockroach is removed,it may live for a few days because:

• A
  the head holds a $1/3^{\text{rd}}$ of a nervous system while the rest is situated along the dorsal part of its body.
• B
  the supra-oesophageal ganglia of the cockroach are situated in the ventral part of the abdomen.
• C
  the cockroach does not have a nervous system.
• D
  the head holds a small proportion of a nervous system while the rest is situated along the ventral part of its body.