Early civilizations of mexico used the solar portion of the 52-year calendar round to

They used it to plan for their farming seasons.

Explanation:

The early civilizations in Mexico used the solar portion of the 52-year calender cycle (also known as “calender round”) to plan for their farming seasons, or periods of cultivation. Generally, the 52-year calendar round was also referred to as "Sacred and Solar cycle": The duration of the Sacred cycle/portion was 260 days, while the duration of the Solar cycle/portion was 365 days. The Solar cycle was regarded as the agricultural calendar because it depended on the sun—solar. Some of the early civilizations of Mexico included the Mayan, the Toltec, and the Olmec civilizations.

d. it gave farmers a way to organize for more political power

confederacy: supported slavery, believed states should be able to nullify federal laws, supported low tariffs

union: everything else