Which of the following is an unsegmented worm with a pseudocoelom.
a. sponge
b. cnidarian
c. arthropod
d. roundworm

The correct answer is option D, Round worm

Roundworm belongs to the phylum  Nematodes and some common characteristics of Nematodes are – they are small, slender , un-segmented, smooth and shiny. Roundworm has   a round body just like a spiny –headed worm which do not have segments . Also they possess a body cavity known as pseudocoel in which the internal body organs lie and the body cavity is not lined with mesodermal cells.  

answer; 60-100; beats per minute

i think its control and coordinate because im pretty sure thats what tissue does and the joints are what control movement and then your skeletal/ bones provides portection. hope that .