Answer:
C. expediting
Explanation:
The options are:
A. confirming
B. expanding
C. expediting
D. contradicting
Maria and Adnan find that the email is quicker than the official company newsletter. This is an example of the speed up or accelerating function of information communication. And precisely it is the expediting function of informal communication. And it is no sort of confirming or authorizing or expanding or increasing or contradicting or challenging function of informal communication. And hence B. expediting is the correct answer.