Identifier name cannot be composed of special characters other than …………… .

1. #
2. Hyphen (-)
3. $\text{\textdollar}$
4. Underscore (_)

Underscore (_)

Reason — In Python, an identifier name can only be composed of letters (both uppercase and lowercase), digits, and underscores (_). Special characters like #, hyphen (-), and $\text{\textdollar}$ are not allowed in identifier names.