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.

2read this passage from "the raven." what is puzzling the speaker in this stanza? 60% but the raven still beguiling my sad fancy into smiling, straight i wheeled a cushioned seat in front of bird, and bust and door then, upon the velvet sinking, i betook myself to linking fancy unto fancy, thinking what this ominous bird of yore- what this grim, ungainly, ghastly, gaunt and ominous bird of yore meant in croaking "nevermore." s and what the raven's message is why the raven came to visit where the raven came from how the raven got into his room