What is the location and function of nephridia?

$A$ student was given a specimen to identify on the basis of the characteristics given below.
$(i)$ They are metamerically segmented.
$(ii)$ Presence of closed circulatory system.
$(iii)$ They have circular and longitudinal muscles for locomotion.
Identify the specimen.

Which of the following animals possesses a closed circulatory system containing blood capillaries?

The first phylum of animals to exhibit a true coelom is:

In which phylum of animals is the digestive tract either straight or coiled?

Suctorial mouth occurs in