In the eyes of anthropologist Payson D. Sheets, ______.
A．because grasses that made up the thatched roof of the dwelling were still new, that the structure was recent
B．he left the site, located northwest of San Salvador, the capital, in 1980 unwillingly
C．by sending radar signals through the ground in order to detect buried objects, he located 22 additional structures still buried in ash
D．when the teeth were found, he said that throwing teeth on the roof is a tradition still practiced by some people in rural El Salvador today