The correct answer is OR.
In Boolean algebra, the overbar stands for the NOT operation, the plus sign stands for the OR operation.
The OR operation is a binary operation that takes two operands, $x$ and $y$, and returns the value $1$ if either $x$ or $y$ is $1$, and returns $0$ if both $x$ and $y$ are $0$.
For example, $1 \lor 1 = 1$, $1 \lor 0 = 1$, $0 \lor 1 = 1$, and $0 \lor 0 = 0$.
The OR operation can be thought of as the logical disjunction of two statements. For example, the statement “It is raining or it is snowing” is true if either it is raining or it is snowing.
The OR operation is a fundamental operation in Boolean algebra, and it is used in many different applications, such as digital logic, computer science, and artificial intelligence.