In which of the following is external fertilization observed?

Identify the organism that is different from others based on the presence of a coelom.

Which character is not the same in $Aves$ and $Mammals$?

In which one of the following is the genus name,its two characters,and its class/phylum correctly matched?

Genus Name	Two Characters $\&$ Class/Phylum
$A$. $Ascaris$	$(i)$ Body segmented,$(ii)$ Males and females distinct; Phylum: $Annelida$
$B$. $Salamandra$	$(i)$ $A$ tympanum represents ear,$(ii)$ Fertilization is external; Class: $Amphibia$
$C$. $Pteropus$	$(i)$ Skin possesses hair,$(ii)$ Oviparous; Class: $Mammalia$
$D$. $Aurelia$	$(i)$ Cnidoblasts present,$(ii)$ Organ level of organization; Phylum: $Coelenterata$

Classify the following animals based on their body symmetry (radial or bilateral): Coelenterates,Ctenophores,Annelids,Arthropods,and Echinoderms.

Trochophore larva is found in