Read the following passage and then answer the questions below. (1.0 pt)

Tet is a national and family festival in Viet Nam which occurs in late January or early February. It is an occasion for every Vietnamese to have a good time thinking about the last year and the next year. Before Tet, people return home after a year of working or studying. At Tet, spring festivals such as rice-cooking, buffalo-fighting and traditional games are usually organized; streets and public buildings are brightly decorated and almost all shops are crowded with people shopping for Tet. At home, people usually clean and decorate their homes. They go to market to buy candy, jams or dried watermelon seeds. They often buy peach blossoms and marigolds because they are traditional flowers on Tet holiday.

Tet is also time for peace and love. During Tet, children often behave well and friends, relatives and neighbors give each other best wishes for the New Year. After Tet holiday, most people will come back to schools, factories, hospitals, and so on to start a new year.

When does Tet occur in Viet Nam?