In which sentence from "Black Hole Beginnings" is a cause underlined?

More matter mounts up on the outside, increasing the pressure on the inside.

As the star material gathers, its inward pressure grows.

The gases blast out as the star goes supernova.

It expands like hot air inside a balloon and pushes outward from the center.

B). As the star material gathers, its inward pressure grows.

Explanation:

As per the question, option B i.e. 'As the star material gathers, its inward pressure grows' involves a cause('the material gathers') underlined that leads to the effect 'growing of inward pressure.' This sentence reflects a cause-and-effect structure as it states an important fact about the beginnings of the Blackhole by displaying the cause or reason i.e. 'gathering of star material' which resulted in the 'growth of inward pressure' that would provide the readers with a better understanding and comprehension. Thus, option B is the correct answer.

The answer is b, as that is a cause and effect relationship.