Gate1998-1 Relational Algebra

Given two union compatible relations R_1(A, B) and R_2(C,D) . What is the Result of Query operation 

R_1 \Join_{ A = C \wedge B = D} R_2


A.   R_1 \cup R_2

B.   R_1 \times R_2

C.   R_1 - R_2

D.   R_1 \cap R_2



Please when you have this type of query , take a small example and solve it. 

So clearly it is an intersection.

By the way, It is also a theta join So directly you can say it is Intersection.