Which of the following pathways is part of the cloaca in vertebrates?

Usually,chordates have red blood containing red blood corpuscles. The blood is red due to the presence of the following pigment:

Vertebrates possess which of the following characteristics?

Non-chordates are characterized by the absence of which of the following features?

What do $a$ and $b$ represent in the given chart respectively?

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