What is a heading? text that tells more about a photograph, illustration, or other graphic text written to explain and give information on a topic a section title within the body of a text that tells the reader something important about the content of that section a short text within a larger text that gives information related but not necessary to the main content

A section title within the body of a text that tells the reader something important about the content of that section

B. 10 to 20 billion years ago.

Explanation:

The Big Bang theory is the dominant cosmological model of the observable universe. This model explains that the universe began to expand from a “point” (often called singularity) of a very high-density and temperature, and from that point, for what is believed to be a time lapse of approximately 13.8 billion years, the universe has continued expanding and evolving. This model is still prevailing because through it, it is possible to explain a large range of observable phenomena in the universe.