An algebraic expression containing three terms is called a

Calculations:

An algebraic expression containing three terms is called a: Trinomial
For example,

the expression 2x² + 3x + 1 is a trinomial.

This expression is composed of three terms: the term 2x², the term 3x, and the constant term 1.

Each term is separated by a plus or minus sign. In this case, all three terms are being added together.

Hence, The Correct option is 3.