"여기가 시청입니까?" "Is this place the city hall?" (b) is the matching sentence. You can think of it as 여기(this place) 가(*) 시청(city hall) 입니까? (is it?), where 가 is a subject marker(particle) with no English equivalent. This is one of the most basic sentences in Korean corresponding to "A is B". - 아는 것이 힘이다: Knowledge is power. (아는 것: knowing, 힘: power) - 하늘이 회색이다: The sky is gray. (하늘: sky, 이: subject marker like 가, 회색: gray) - 나는 학생입니다: I am a student. (나: I, 는: subject/topic marker, 학생: student) * 입니까 is the question form of 입니다 (is; 이다, 이에요, 예요, 이야 are equivalents of it).

I'd like to point out though that if the context is talking to a friend, that ending/speech level is probably too formal^^ I don't have a Korean keyboard right now, but it would be "ee-eh-yo".