Which two ancient civilizations practiced human sacrifice Maya and Inca
Maya and Omac
Aztec and Inca
Maya and Aztec

Maya and Inca but Aztec could be in there too

Explanation:

The Incas performed child sacrifices during or after important events, such as the death of the Sapa Inca (emperor) or during a famine

Generally only high status prisoners of war were sacrificed, with lower status captives being used for labour. Human sacrifice among the Maya is evident from at least the Classic period (c. AD 250–900) right through to the final stages of the Spanish conquest in the 17th century.

In addition to slicing out the hearts of victims and spilling their blood on temple altars, the Aztecs likely also practiced a form of ritual cannibalism. An Atztec human sacrifice atop the Mesoamerican temple pyramid.

The study of where things are 

Answer decreased soil salinity;