Which of the following phyla is the first to possess a complete digestive system?

What type of epidermis is found in Ascaris?

Which of the following animals is a pseudocoelomate?

While trying to find out the characteristics of a newly found animal,a researcher performed histology on the adult animal and observed a cavity with the presence of mesodermal tissue towards the body wall,but no mesodermal tissue was observed towards the alimentary canal. What could be the possible coelom of that animal?

$Ascaris$ has three lips. Identify their arrangement.

In pseudocoelomate organisms,excretion occurs through which of the following structures?