What caused the pottery to turn black?
a. they were allowed to always be exposed to the air.
b. they were allowed to always be exposed to rain.
c. when they were covered with manure, oxygen was increased.
d. when they were covered with manure, oxygen was reduced.
select the best answer from the choices provided

The correct answer is D) when they were covered with manure, oxygen was reduced.

What caused the pottery to turn black was that when they were covered with manure, oxygen was reduced.

We are talking about Native arts in New Mexico, in the 1920s. Black pottery was a true art for artisans in Native New Mexico. This technique allowed them to charge a little bit more for their pieces of work. They considered black pottery special and that is what they said when they were trading it. One of the towns were artisans developed the black pottery technique was San Idelfonso, New Mexico.