In which phylum do animals have a digestive tract that opens at only one end?

How many intermediate hosts do trematode parasites require to complete their life cycle?

In the secondary host,the transmission of $Taenia$ occurs in the form of:

Given below are two statements.
Statement $I$: Cephalic ganglion appears like $U$ shaped structure in Hydra.
Statement $II$: Ventral nerve cords are connected to each other by commissure in a ladder like manner in Planarian.
In the light of above statements,choose the most appropriate answer from the options given below:

Which of the following organisms has only a single opening that serves as both the mouth and the anus?

The liver fluke ($Fasciola$ $hepatica$) completes its life cycle in which two hosts?