The logic circuit shown in figure yields the following truth table. The gate X in the diagram is
A | B | C |
1 | 1 | 1 |
0 | 1 | 1 |
1 | 0 | 1 |
0 | 0 | 0 |
From the second and fourth row, for C to be satisfied, X should be AND gate.
The output from the truth table is possible if the unknown gate is an AND gate