When the heart of a frog is removed from the body,it continues to beat for some time. Select the correct statement$(s)$ from the following:
$(i)$ The frog is a cold-blooded animal.
$(ii)$ The frog does not have a heart-based circulatory system.
$(iii)$ The heart has myogenic properties.
$(iv)$ The heart is self-excitable.

• A
  Only $III$
• B
  Only $IV$
• C
  $I$ and $II$
• D
  $III$ and $IV$