Select the total number of correct statements from the following about coelenterates.
I. Most of the coelenterates are solitary
II. They (coelenterates ) have three types of nematoblasts
III. The interstitial cells present are undifferentiated mesenchyme cells with a capability to convert in any type of epithelial cells.
IV. Non-polar neurons are scattered irregular in the body.
V. They exhibit alterantion of generation