Select the correct option for Non-chordates:
$(I)$ Central nervous system is ventral,solid,and double
$(II)$ Gill slits are absent
$(III)$ Heart is ventral
$(IV)$ Post-anal tail is absent

Which of the following statements are true for the phylum $Chordata$?
$(a)$ In $Urochordata$,the notochord extends from head to tail and is present throughout their life.
$(b)$ In $Vertebrata$,the notochord is present during the embryonic period only.
$(c)$ The central nervous system is dorsal and hollow.
$(d)$ $Chordata$ is divided into $3$ subphyla: $Hemichordata$,$Tunicata$,and $Cephalochordata$.

Which of the following is $NOT$ found in invertebrates?

Statement-$1$ : Cephalochordata bears notochord all along the body throughout life.
Statement-$2$ : Urochordate bears vertebral column only in tail region throughout the life.
Then which is correct?

Apart from Annelida and Arthropoda,metamerism is also exhibited by ............ .

Which of the following is $NOT$ included in Protochordata?