In which of the following is external fertilization observed?

Which of the following groups contains only hermaphrodite (bisexual) animals?

Choose the correct option for the following statements:
$(i)$ Metamerism is a characteristic feature of $Annelida$ / $Arthropoda$.
$(ii)$ Internal buds in sponges are called $Gemmules$ / $Gemmi$.

Consider the following statements:
$A$. Annelids are true coelomates
$B$. Poriferans are pseudocoelomates
$C$. Aschelminthes are acoelomates
$D$. Platyhelminthes are pseudocoelomates
Choose the correct answer from the options given below:

Match the following:

$(a)$ Operculum	$(i)$ Ctenophora
$(b)$ Parapodia	$(ii)$ Mollusca
$(c)$ Scales	$(iii)$ Porifera
$(d)$ Comb plates	$(iv)$ Reptilia
$(e)$ Radula	$(v)$ Annelida
$(f)$ Hairs	$(vi)$ Cyclostomata and Chondrichthyes
$(g)$ Choanocytes	$(vii)$ Mammalia
$(h)$ Gill slits	$(viii)$ Osteichthyes

Which of the following organisms possess an open-type circulatory system?