The given figure shows some characteristic features marked as chordates. Identify the correct labelling A,B,C and D. 

A. A-Notochord; B-Post-anal part; C-Gill slits; D-Nerve cord

B. A-Nerve cord; B-Notochord; C-Post-anal part; D-Gill slits

C. A-Notochord; B-Nerve cord; C-Gill slits; D-Post-anal part

D. A-Gill slits; B-Post-anal part; C-Nerve cord; D-Notochord