The I-V characteristics of the element between the nodes X and Y is best depicted by

\( {Graph (A)} \) 
\( {Graph (B)} \) 
\( {Graph (C)} \) 
\( {Graph (D)} \) 
Two p-n junction diodes \(D_1\) and \(D_2\) are connected as shown in the figure. \(A\) and \(B\) are input signals and \(C\) is the output. The given circuit will function as a _______. 