31.

Read the following passage and mark the letter A, B, C or D to indicate the best answer to each of the questions from 31 to 35.
CELEBRATION OF TET
Tet, or Lunar New Year, is the most important traditional festival in Vietnam. It usually falls in late January or early February. Before Tet, people often clean and decorate their homes, buy new clothes, and prepare special foods like Banh Chung and Banh Tet. Families gather together, and children receive "lucky money" in red envelopes from adults.
During Tet, many families visit their relatives and friends, exchanging good wishes for the new year. People also go to pagodas or temples to pray for good health and happiness. It's a time for joy, family reunions, and looking forward to a prosperous year ahead. Fireworks displays are common in big cities on Tet Eve, bringing excitement to everyone. Although Tet traditions vary slightly from region to region, the spirit of Tet – a time of renewal and hope – remains the same throughout Vietnam.
What is the main idea of the passage?