Unsegemented worms that are pseudocoelomates and have two body openings to their digestive systems are (a) Porifera (b) Arthropoda (c) Cnidaria (d) Nematoda.

(d) Nematoda.

Explanation:

Pseudocoelomate organisms are animals that possess a pseudocoelom (not a true coelom). A perfect example of animals that are pseudocoelomate are those that belong to the phylum Nematoda. They include roundworms, hookworms etc. A pseudocoelom is a cavity containing fluid which immerses the internal organs of a nematode.

Their physical structure is triploblastic and bilaterally symmetrical. They have two body openings that links to their digestive system, but do not possess a stomach.

Animals that belongs to phylum Arthropoda are coelomate organisms, meaning they possess.

Animals that belongs to phylum Cnidaria are acoelomate organisms, meaning they do not posses coelom.

Animals that belongs to phylum Porifera are acoelomate organisms.