It's b. A bus that operates inside one city
There are certainly both pros and cons to using email messages.
Pros:
Email travels instantaneously, no need to wait for reply
Email can reach anyone with internet, regardless of location
Cons:
Users with email can spam one another by sending messages constantly
User must have access to the internet to receive email
Basically, email is useful because anyone with internet can send messages to anyone else who has internet, but both users must, of course, first gain access to the internet.
So you're looking for 2 synonyms. B is the best answer, avert and prevent are synonyms of each other. The other choices are antonyms, or they're at least not synonyms.
Answer:
C. It contains strong and accurate details that oppose the writer’s position
