The religious meaning explains the correct category.
In Christian tradition, the Holy Spirit enables Jesus’s followers to spread his message. Pentecost refers to that tradition. This explains a religious belief; it does not require learners to profess it personally.
In the church year, Pentecost is celebrated in relation to Easter. Its calendar date therefore changes from year to year. For this question, connect its name with Christianity; no particular date is requested.

The other three answers
The other answers confuse the type of occasion.
German day of remembrance.
A German day of remembrance commemorates a particular historical or social occasion. Here, Pentecost is classified as a Christian festival, not a national commemoration.
international day of mourning.
Pentecost is not an international day of mourning in this question. Its Christian meaning concerns the Holy Spirit and the spreading of faith.
Bavarian tradition.
The festival is not confined to Bavaria. Regional customs may accompany a festival without determining its fundamental religious classification.
Religious festival, statutory holiday and personal routine differ.
Statutory holidays are determined by applicable law. For example, Bavarian holiday law explicitly lists Whit Monday. Calling the festival Christian instead explains its religious background.
A statutory holiday does not oblige anyone to attend worship. Nor does an outing or family gathering on that day establish a person’s religious beliefs.
Pentecost · Christian festival · Evangelical Church in Germany ↗Pentecost belongs to the Christian church year.
Remember the festival’s category. The question does not assess anyone’s religious membership.
Three words for this question
- PfingstenPentecost or Whitsun
- A Christian festival associated with the Holy Spirit.
- das Kirchenjahrchurch year
- The annual sequence of church festivals and seasons.
- der Gedenktagday of remembrance
- A day devoted to remembering a particular event or subject.
