Match the entries in column I and column II.

Column I		Column II
P	Notochord and hollow nerve cord present	i.	Chordata
Q	Ectoparasite with 6–15 pairs of gills and closed circulation	ii.	Cyclostomata
R	Marine animals with persistent notochord and placoid scales	iii.	Chondrichthyes
S	Animals with open circulatory systems, and stomochord	iv.	Hemichordata

• Correct answer
  A

  $P - iv; \quad Q - i; \quad R - ii; \quad S - iii$
• B

  $P - iv; \quad Q - ii; \quad R - i; \quad S - iii$
• C

  $P-i ; \quad Q-i i i ; \quad R-i i ; \quad S-i v$
• D

  $P-i i i ; \quad Q-i ; \quad R-i i ; \quad S-i v$

Hence, the correct answer is option: 'A'.