TEZPUR 2025 — Computer PYQ

The correct answer is (d) x.

In computer programming, a variable is a symbolic name (an identifier) that references a specific location in memory used to store data. In contrast, items enclosed in quotes are treated as literal strings, and numbers are treated as literal integers.

• x: This is a valid identifier (variable name). It can be assigned a value, such as $x=10$.

• 'x' and "x": These are string literals. They represent the character 'x' itself, not a storage location.

• 5: This is an integer literal. It represents the value five directly.

We can illustrate the distinction through an assignment operation in a programming context:

$$Variabl{e}_{Assignment}:x=5$$

In this equation, $x$ acts as the memory reference, while $5$ is the value being stored. If we attempt to treat a literal as a variable, the logic fails:

$${}^{\prime }{x}^{\prime }=5⟹\text{Invalid (Syntax Error)}$$

Since only $x$ functions as an identifier that can hold varying data, it is the only variable in the provided list.