The correct option is D Elections held in one or more constituencies due to the death or resignation of candidates.
When elections are held in one or a few constituencies due to the death or resignation of candidates, it is called a by-election. It can also be held if an elected member resigns or gets disqualified under parliamentary law.
Sometimes, Lok Sabha or Vidhan Sabha might be dissolved before they complete their five-year term. Elections held in such scenarios are known as midterm elections.
If elections happen after completion of the five year term of the legislature, then it is called a general election.