Which of the following sentences demonstrate correct parallel structure? a. the young man crept across the arid desert, he rode on the back of an old camel, and swam across the vast ocean in search of truth. b. the young man crept across the arid desert, rode on the back of an old camel, and swam across the vast ocean in search of truth. c. the young man was creeping across the arid desert, riding on the back of an old camel, and swam across the vast ocean in search of truth. d. the young man crept across the desert, rode on the back of a came, and he swam across the ocean in search of truth.