GeeksForGeeks Mock test 1 2017: Databases - Relational Algebra

Question

Consider the following collection of relation schemes:

professor(profname, deptname)
department(deptname, building)
committee(profname,commname)

Find all the professors who are in exactly (i.e., no more and no less) all those committees that Professor Smith is in.

A	R2 <- Πcommname(Πprofname(committee)) R3 <- Πcommname(committee) - R2 (committee / R2) - σprofname = Smith(committee ⋈ R3)
B	R2 <- Πcommname(Πcommname(committee)) R3 <- σprofname = Smith(committee) - R2 (committee / R2) - Πprofname(committee ⋈ R3)
C	R2 <- Πcommname(σprofname = Smith(committee)) R3 <- Πcommname(committee) - R2 (committee / R2) - Πprofname(committee ⋈ R3)