During which eon were the oceans made of liquid rock?
a. hadean
b. archean
c. proterozoic
d. phanerozoic

The correct answer is option A. Hadean.

Explanation:

The Hadean eon is in the Precambrian era.

During this era the earth began to form from the gas and dust that circulated around the sun.

The oceans of this era were formed of liquid rock and the atmosphere was heavy, since it was composed of carbon dioxide with hydrogen.

Then the carbon dioxide was disappearing because the processes of subduction and water dissolution occurred in the ocean.

Given this information we can say that the correct answer is option A.

the missing space is phylum