Match List - I with List - II and choose the correct answer.

List - I	List - II
(a) Metamerism	(i) Coelenterata
(b) Canal system	(ii) Ctenophora
(c) Comb plates	(iii) Annelida
(d) Cnidoblasts	(iv) Porifera

To find the correct match between List - I and List - II, let us analyze each feature and associated animal phylum step-by-step:

1. (a) Metamerism: Metamerism is the phenomenon of having a linear series of body segments fundamentally similar in structure (metameres). It is a defining characteristic of Phylum Annelida (such as earthworms). Thus, (a) matches with (iii).
2. (b) Canal system: The water canal system (or aquiferous system) is a unique and characteristic feature of sponges, which belong to Phylum Porifera. Water enters through microscopic pores (ostia) into a central cavity (spongocoel) and exits through the osculum. Thus, (b) matches with (iv).
3. (c) Comb plates: Comb plates are rows of ciliated plates used for locomotion, which are the hallmark feature of sea walnuts or comb jellies belonging to Phylum Ctenophora. Thus, (c) matches with (ii).
4. (d) Cnidoblasts: Cnidoblasts (or cnidocytes) are specialized stinging cells containing nematocysts, used for anchorage, defense, and capture of prey. These are characteristic of Phylum Coelenterata (also known as Cnidaria). Thus, (d) matches with (i).

Combining these matches, we get:
a - (iii)
b - (iv)
c - (ii)
d - (i)

Therefore, the correct option is a - (iii) b - (iv) c - (ii) d - (i).