The plain of Jars, in north east Laos. Is one of the oldest archeological mysteries in Southeast Asia. Located on the plateau of Xieng Khouang, in the mountains

The plain of Jars, in north east Laos. Is one of the oldest archeological mysteries in Southeast Asia.
Located on the plateau of Xieng Khouang, in the mountains of Indonesia, there are about 90 different jars sites. Each site contains from 1 to 400 jars. It has been estimated that they were created 3,000 years ago, and conglomerate, limestone, granote, breccias and conglomerate, with the majority being made of sandstone. The tallest jar is about 9 feet tall and all are made from their own individual slab of stone.
At first glance the jars appear to haphazardly placed, with some standing upright and others on their sides, pointing in different directions. Further studies have revealed that they are placed in positions that form the constellation patterns of the stars. There has been lost of speculation about the purpose of the jars drinking glasses for a giant race, being used to collect rainwater, or as burial urns.
Most of the jars are empty, but a few have been found with bodies or tools inside, or filled with miniature Buddha statues. Exploration is hard as the area is littered with unexploded bombs from the Secret War.

20. Why does the writer write the text ?
a. To discover the mystery of the plain of jars.
b. To tell the readers about a sacred place in Laos
c. To share information about a specific historical place
d. To express his/her amazement towards the plain of jars.
21. Who will be more insterested to read articles about the jars ?
a. Geologist
b. Historians
c. Sociologist
d. Archaeologists
22. “Further studies have revealed that they are placed in positions.....” (Paragraph 3)
The underlined word refers to.......
a. The jars
b. The stars
c. The studies
d. The constellation forms