13) Read the following excerpt from 'Closer to the origin of the universe', March 2000 issue of Fapesp magazine: The universe, the Milky Way, the ...

13) Read the following excerpt from 'Closer to the origin of the universe', March 2000 issue of Fapesp magazine:

The universe, the Milky Way, the spiral galaxy to which the solar system belongs, was quite different when it took shape about 15 million years ago.
When it formed, it was nothing more than a huge cloud of gas consisting mainly of hydrogen and helium, the simplest atoms that exist.
Billions of years later, most of the heavier chemical elements - oxygen, carbon, and others that also form stars and planets in smaller proportions - were formed.
The detailed understanding of the formation and evolution process of the galaxy, which in the case of the Milky Way amounts to 200 billion stars, can lead to a clearer model of the origin and evolution of the universe itself.
Astronomer Walter Junqueira Maciel, from the Astronomical and Geophysical Institute (IAG) of USP, was able to detail how chemical elements change over time. Maciel and one of his graduate students showed that the abundance of metallic chemical elements, represented by iron, must have increased at least four times after the Milky Way appeared.
Maciel says that the larger and older stars no longer appear in the sky. They have probably already died, but they have left a precious record, the abundance of metals that form throughout their history, the so-called stellar abundance, and thus it is possible to go back to the approximate time when the stars were born.
A) Hydrogen
B) Second
C) Kelvin
D) Mole
E) Ampere