Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the option that best fits each of the numbered blanks.

Vietnam is a country rich in cultural diversity, with 54 ethnic groups living together. Each ethnic group has its own unique traditions, languages, clothing, and customs, 15 _______. The largest ethnic group is the Kinh, who mainly live in lowland arcas and cities. Other groups, such as the Tay, Thai, H'Mong, Dao, and Khmer, live in mountainous and rural regions 16 _______.
One example of cultural diversity in Vietnam is the variety of festivals. The Tet (Lunar New Year) Festival, celebrated by the Kinh, is the most important holiday in the country. Meanwhile, 17 _______, such as the Gau Tao Festival of the H'Mong people, which prays for good fortune, or the Cha Chien Festival of the Cham people, which honors their ancestors.
Traditional clothing also reflects cultural diversity. 18 _______, while ethnic minorities wear colorful handmade clothes with unique embroidery patterns.
Despite differences in languages and customs, 19 _______, respecting and preserving their traditions. This rich cultural diversity makes Vietnam a fascinating country with a deep and vibrant heritage.