Question

the library discovery
ellie stepped into the library, her shoes making soft taps on the stone floor. the air smelled faintly of old paper and something else she couldnt quiet identify, like the distant sent of rain.
rows of towering bookshelfs stretched toward the ceiling, their tops disappearing into shadows. the light from the tall, arched windows cast long streaks of gold across the room, highlighting the dust that swirled lazily in the air. ellie paused, feeling as if the library itself were watching her.
she wandered through the ailes running her fingers along the spines of books. some were smooth and new, while others were cracked and faded, their titles barely visible. in the center of the library stood a large circular table and on it lay a single, open book. the pages were filled with writing that seemed to shimmer faintly, as if the ink itself were alive. ellie couldnt resist. she reached out, her hand trembling slightly, and turned the page.
the words rearranged themselves as she stared, forming a message: \look beyond the shelves.\ her breath caught she spun around, searching for something out of place. on the far wall, she noticed a tiny, ornately carved door she hadnt seen before. she walked slowly toward it, her heart pounding in her chest. the door was barely big enough to crawl through. ellie hesitated, then pushed it open, revealing a staircase spiraling downward into the darkness.

1. which revision best corrects the sentence: \her breath caught she spun around, searching for something out of place?\

her breath caught, she spun around, searching for something out of place.
her breath caught and spun around, searching for something out of place.
her breath caught. she spun around, searching for something out of place.
her breath caught; she spun around, searching for something out of place.

Explanation:

The original sentence "Her breath caught she spun around, searching for something out of place" has a run - on error. A comma should be added after "caught" to separate the two independent clauses.

Answer:

Her breath caught, she spun around, searching for something out of place.