What is an algebraic expression ?
A.An expression having one or more variables
B.An expression having one or more forms
C.An expression having a constant value
D.Cannot be defined

Hint: An algebraic expression consists of variables and constants. Hence it's an expression having one or more variables.

Complete step-by-step answer:
An algebraic expression in mathematics is an expression which is made up of variables and constants along with algebraic operations (addition, subtraction, etc.) Expressions are made up of terms.
3x + 4y – 7, 4x – 10, etc.
These expressions are represented with the help of unknown variables, constants and coefficient. The combination of these three (as terms) is said to be an expression
From this we see that an algebraic expression is an expression having one or more variables .

The correct option is A.

Note: Algebraic Expressions shouldn’t be confused with algebraic equations. An algebraic equation has two sides (Left Hand Side and Right Hand Side ) whereas an algebraic expression does not.