Fishes,amphibians,reptiles,and birds are kept in the same

$A$ schematic representation of a chordate's embryo is shown in the figure. The structures marked $A, B, C$ and $D$ are respectively:

Retrogressive metamorphosis is found in

Which of the following is incorrect for $Urochordata$?

One of the primary characters of chordates is

Select the correct option for the following matches regarding Chordates:

$(1)$ Notochord present only in larval stage.	$(a)$ Chordata
$(2)$ Notochord present throughout life.	$(b)$ Vertebrata
$(3)$ Notochord is replaced by vertebral column.	$(c)$ Cephalochordata
$(4)$ Notochord is mesodermal in origin.	$(d)$ Urochordata