What are Arturo Montero and Guillermo de Anda NOT investigating in the cenote？ （Text 1A）（）

A. whether the ancient Maya had depleted the cenote’s water from overuse

B. whether the ancient Maya went there to give thanks and offer sacrifices

C. whether the ancient Maya used the cenote as a sundial and timekeeper

D. whether ancient Maya priests used the cenote to correct their measurements of the sun’s angle when it reached the zenith