Direction: In the following passage, some words have been deleted. Fill in the blanks with the help of the alternatives given. Select the most appropriate option for each blank.

Many ancient civilizations had complex writing systems that archaeologists (1)_____ linguists are still working to decipher. The written system of the Mayan language, for instance, (2)______ a mystery to scholars until the 20th century. The Maya were one of the most powerful pre-Columbian (3)______ in North America, and (4)_____ Central American temples and manuscripts are inscribed (5)______ a collection of squared glyphs or symbols.