Cordless telephone system will not work under which of the following

Cordless telephone system will not work under which of the following criteria?

A. Within a home

B. Within a building

C. Within campus

D. Within a city

I got this question in an international level competition.

I’d like to ask this question from Cordless Telephone Systems topic in division Introduction to Wireless Communication Systems of Wireless/Mobile

Correct answer is D. Within a city

Easy explanation: Cordless telephones are used in homes, in offices, on campus, at trade shows. But due to their limited coverage they cannot cover a whole city.