"in recent years, resources such as Twitter have been a great way for us to monitor the words that people are using informally in particular parts of the world," she said.

why did the author use the word "monitor"?

a. to suggest that the OED has access to the private accounts of users on social media websites.

b. to indicate that the OED's editors have been studying the way people use words informally online.

c. to reveal that some twitter users are collaborating with the OED to define the informal words used online.

d. to explain that the OED is interacting with people on twitter to learn how to use regional words accurately.