PLEASE HURRY Which group of sentences best uses a variety of sentence patterns to convey meaning and the relationship between ideas?

(a) Although no one was behind him, he jumped because of a sudden noise. He thought he was alone. Because he was afraid, he kept walking.

(b) He heard a noise and jumped, but no one was behind him. So he kept walking, but he was afraid. So he glanced backed over his shoulder, but he was alone.

(c) There was a sudden noise. He jumped. No one was behind him. He kept walking. He glanced back over his shoulder. He was alone. He was afraid.

(d) He jumped at the sudden noise, but no one was behind him. So he kept walking, glancing back over his shoulder to make sure he was alone.