Read the excerpt from Neil deGrasse Tyson’s “Death by Black Hole.”

Black holes are regions of space where the gravity is so high that the fabric of space and time has curved back on itself, taking the exit doors with it. Another way to look at the dilemma: the speed required to escape a black hole is greater than the speed of light itself. . . . light travels at exactly 299,792,458 meters per second in a vacuum and is the fastest stuff in the universe. If light cannot escape, then neither can you, which is why, of course, we call these things black holes.

Which of the following features would best enhance the reader’s understanding of this excerpt?
a photograph of a black hole
a demonstration of the speed of light
an interactive animation of a black hole
a definition of the term black hole