Respiration in cephalochordates occurs through

The notochord is an organ derived from which embryonic layer?

$A$: All chordates have kidneys as excretory organs.
$R$: Kidneys help in the removal of metabolic wastes along with regulating the osmolarity of body fluids.

Definition / Explanation: Notochord

Select the correct statements with reference to chordates.
$A$. Presence of a mid-dorsal,solid and double nerve cord.
$B$. Presence of closed circulatory system.
$C$. Presence of paired pharyngeal gill slits.
$D$. Presence of dorsal heart.
$E$. Triploblastic pseudocoelomate animals.
Choose the correct answer from the options given below:

The notochord is derived from which of the following germ layers?