What should replace the underlined pronoun to correct the pronoun shift error

Which of the fallowing is true about plays

Which sentence best contrasts two things? a. air travel, like bus travel, is a fun way to get from one place to another. b. air travel is a fun and relatively easy way to get from place to place. c. both bus travel and air travel require substantial planning. d. air travel is much more expensive than bus travel.

Match the description to the term. 1. textbooks conference usage 2. elements surround a word which clarify the meaning casual usage 3. the way in which english is used context 4. family and friends frozen usage 5. friends at a football game formal usage 6. teachers and employers intimate usage 7. making an appointment usage