Question

the occured first. this event is when happened the second era was in this radiation era matter era

Explanation:

To solve this, we analyze the cosmic eras:

Step 1: Identify the first era

In cosmic history, the Radiation era occurred first. This era was dominated by high - energy radiation (like photons) and took place in the early universe, right after the Big Bang, when radiation was more influential than matter.

Step 2: Identify the second era

After the Radiation era, the Matter era followed. In the Matter era, matter (such as atoms, stars, galaxies) became the dominant component of the universe as the universe expanded and cooled, reducing the dominance of radiation.

Answer:

First dropdown: Radiation era
Second era: Matter era

(Note: For the middle dropdown (describing the first event), typical options related to the Radiation era’s key event would be something like "radiation dominated the universe" or "the early universe was filled with high - energy radiation and elementary particles", but since the exact options aren’t fully visible, the core era order is Radiation era first, then Matter era.)